Case No: A3/2017/0813
Neutral Citation Number: [2018] EWCA Civ 2219
IN THE COURT OF APPEAL (CIVIL DIVISION)
ON APPEAL FROM THE HIGH COURT OF JUSTICE
CHANCERY DIVISION, PATENTS COURT
John Baldwin QC
[2017] EWHC 42 (Pat)
Royal Courts of Justice
Strand, London, WC2A 2LL

Date: 10/10/2018
Before:

LORD JUSTICE LONGMORE
LORD KITCHIN
and
LORD JUSTICE FLOYD

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Between:

	ICESCAPE LIMITED	Claimant/ Respondent	
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	ICE-WORLD INTERNATIONAL BV & ORS	Defendants/Appellants	

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Daniel Alexander QC, James Tumbridge and Ashton Chantrielle (instructed by Venner Shipley LLP) for the Appellants 
Douglas Campbell QC (instructed by Clarke Willmott LLP) for the Respondent

Hearing dates: 26th- 27th June 2018

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Judgment
Lord Kitchin:  
1.	This appeal concerns a system for cooling mobile ice rinks. The appellants (collectively “Ice-World") make mobile ice rinks and lease them to third parties. They are the proprietors of EP (UK) 1,462,755 entitled “Cooling member for a mobile ice rink" (“the patent”). The patent claims a priority date of 24 March 2003.
2.	The respondent (“Icescape”) operates mobile ice rinks and also leases those ice rinks to third parties. For a time and following the acquisition of the business of an unrelated company, Icescape operated a mobile ice rink made and leased to it by Ice-World. When that relationship came to an end, Icescape designed, made and began to operate its own mobile ice rink, and it was these activities which led to these proceedings.
3.	In May 2015 Ice-World wrote to Icescape asserting that Icescape’s mobile ice rink infringed the patent. Then, in May 2016 Ice-World sent letters to Icescape and a large number of its actual and potential customers asserting infringement. In June 2016 Icescape issued these proceedings complaining of the May 2016 letters and seeking relief for groundless threats of infringement, revocation of the patent and a declaration that none of its activities infringed the patent.  Revocation was sought on the ground that the patent was not entitled to its claimed priority date and that it was invalid as a result of Ice-World’s own prior uses. Ice-World responded, disputing that the patent was invalid and alleging infringement. It accepted that it had written threatening letters but maintained that those threats were justified. It also contended that if, contrary to its primary case, the patent was invalid, it had a defence to the claim for threats under s.70(2A) of the Patents Act 1977 (“the 1977 Act”) on the basis that it did not know and had no reason to suspect that the patent was invalid in that respect. 
4.	The action came on for trial in December 2016 before Mr John Baldwin QC sitting as a deputy judge of the Patents Court of the High Court. It lasted for three days. It was common ground by that stage that the patent was invalid if it was not entitled to its claimed priority date. It was also common ground that the letters constituted threats of patent infringement proceedings. So the issues for the judge were:
i)	whether the patent was entitled to priority;
ii)	whether the mobile ice rink made by Icescape fell within the scope of the patent;
iii)	whether, on the assumption the patent was invalid but, had it been valid, would have been infringed, Ice-World had a defence to the claim for unjustified threats under s.70(2A) of the 1977 Act.          
5.	The judge gave judgment on 23 January 2017 ([2017] EWHC 42 (Pat)). He found in favour of Icescape on each of the three issues before him. Ice-World now appeals to this court against his findings. I will deal with the three issues in turn but first I must say a little about the technical background and describe the disclosure of the patent.
The technical background 
6.	Mobile ice rinks comprise a refrigeration unit, a coolant, manifolds, an array of pipes and a pump which drives the coolant from the refrigeration unit through a feed manifold and into the array of pipes which extend under the ice field and then through a discharge manifold to the refrigeration unit. A typical arrangement of these components at the priority date is acknowledged in the patent and comprised a unit consisting of a series of parallel longitudinal pipes extending along the length of the ice field and, running in an orthogonal direction, a feed manifold and a discharge manifold. Pairs of parallel pipes could be connected together at one end by a U-shaped transverse pipe of some kind and could be connected at the other end by flexible pipe sections to the feed manifold or the discharge manifold. In this way and by the use of appropriate connections to either the feed or the discharge manifold, a fluid path for coolant could be formed from the feed manifold to the discharge manifold through two parallel and interconnected pipes. Further, a number of units could be arranged in series across the width of the ice field with their manifolds connected together by standard fluid tight connectors.   
7.	This general structure is also reflected in the judge’s findings of the common general knowledge which he set out at [16]:
“16.1  Ice rinks are created by the distribution of and flow of coolant through an array of pipes embedded within a water surround.
16.2  In operation, coolant is distributed through the system using a pump and a cold feed line. Once the coolant arrives at the ice field it is distributed via a number of manifolds arranged in series, each of which contains a number of branches. For transport to and from site purposes, each manifold is limited in length to about 6m. These manifolds are also known as headers or collectors and when connected together they are laid one after the other down the width of the ice field.
16.3 The manifolds are connected to one another with an industry standard fluid tight connector, either a flange or other mechanical coupler.
16.4  Branches off the manifolds are connected to longitudinal pipes which are perpendicular to the axis of the manifold and travel across the length of the ice field.
16.5  These longitudinal pipes are laid by alternating a flow line next to a discharge (return) line in pairs. At the opposite end of the ice field from the manifold, a return connection is made between each pipe in a given pair using either a secondary manifold (with a series of branches) or an individual "u-shaped" coupling - either of which joins the flow and discharge pipes to each other to form a loop.
16.6  The coolant passes through the feed manifold, through the "out" longitudinal pipes, back through the associated "return" longitudinal pipes, back into the discharge manifold and then to the refrigeration unit for re-cooling and further circulation.
16.7  The lengths of the manifolds and longitudinal pipes are chosen based on convenience of transport and the size of rink required.
16.8 The individual lengths of the longitudinal pipes are connected and disconnected from each other on assembly and disassembly of the system.
16.9  Trucks for transporting mobile ice rinks and components thereof can typically deal with items several metres (say up to 7m) in length but not much longer.”
8.	The problem with these prior art systems is described in the patent at [0003]. In summary, their installation and dismantling required all of their various components to be assembled and then disassembled and this was laborious, relatively time consuming and expensive. Further, leakage could occur as a result of the need to assemble all of the different components, and this could cause delay.  
The patent  
9.	The invention of the patent addresses this problem and aims to provide a cooling member for an ice rink which can be installed (and dismantled) rapidly and which allows the rink to be made with different surface areas.
10.	An embodiment of the claimed invention is illustrated in figure 8:

11.	Various aspects of this arrangement merit description at his point. First, it includes multiple elements (41, 42) each of which has a feed manifold (43, 45) and a discharge manifold (44, 46). These multiple elements are placed adjacent to each other so that, in the words of the patent, the feed and discharge manifolds of the elements “extend in the extension of one another in the transverse direction” and are “provided with a coupling member (47, 48) to make a fluid-tight connection between the respective feed and discharge manifolds of the first and the second element”.   
12.	Secondly, a number of longitudinal pipes (50, 51) are connected to each manifold such that the feed pipes (50) are connected to the feed manifolds and the return pipes (51) are connected to the discharge manifolds, and these two sorts of pipe are connected to each other through the connecting pipe (63) and via the flexible connectors (65, 66). 
13.	Thirdly, each longitudinal pipe is made up of a number of rigid and mutually parallel series of pipe sections that are connected to one another in a fluid-tight manner via a joint member (70). This joint member is flexible and allows the connected pipe sections to fold relative to each other for the purposes of transportation. In the words of the patent at [0005]: “Each longitudinal pipe comprises at least two rigid pipe sections that are connected to one another via a joint member such that they are fluid-tight, and wherein by moving the joint members a first series of parallel pipe sections can be placed in a transport position with respect to a second series of parallel pipe sections connected thereto, in which transport position the two series of pipe sections are at an angle with respect to one another or are positioned on top of one another, and can be placed in an operational position in which the two series of pipe sections extend in the extension of one another.”
14.	The benefits of this system are described at [0006]. The cooling elements can be delivered in the transport position, for example folded on top of each other. Before transport, the pipe sections and joint members can be pressure tested for fluid tightness at a test location. When the assembly arrives at the desired location, the longitudinal pipes can be folded open and placed on the ground. The manifolds can be coupled to one another in the transverse direction and connected to a source of coolant. The patent then explains that, because the longitudinal pipes have been connected to one another in a fluid tight manner prior to assembly and retain their fluid tightness in the transport position, assembly of the ice rink can take place very rapidly. The rink can be made to a desired length by using a greater or smaller number of longitudinal pipe sections and joint members, and it can be made to a desired width by coupling together a greater or smaller number of manifolds.
15.	That brings me to claim 1 which is the only claim with which we need be concerned. The deputy judge set it out this way (with the letters A-E added for convenience):  
“Cooling member (21, 40) for a mobile ice rink provided with:
a feed manifold (43, 45) extending in a transverse direction and a discharge manifold (44, 46), and
a number of longitudinal pipes (50, 51) which extend transversely to the manifolds and can be connected at a first end (53, 54) to a manifold (43, 44, 45, 46), two longitudinal pipes (50, 51) in each case being in fluid communication with one another at a second end (60, 61) via a connector (27, 63), so that a fluid path is formed from the feed manifold (43, 45) to the discharge manifold (44, 46) via the two connected longitudinal pipes (50, 51),
characterised in that
A.  the cooling member comprises at least two elements (41, 42), each with a feed manifold (43, 45) and discharge manifold (44, 46) and a number of longitudinal pipes (50, 51) connected thereto,
B.  wherein each longitudinal pipe comprises at least two rigid pipe sections (3, 12, 16, 24, 68, 69) that are connected to one another via a joint member (4, 13, 17, 25, 70, 132, 133) such that they are fluid-tight, and
C.  wherein by moving the joint members (4, 13, 17, 25, 70, 132, 133) a first series of parallel pipe sections (68, 68', 68") can be placed in a transport position with respect to a second series of parallel pipe sections (69, 69', 69") connected thereto, in which transport position the two series of pipe sections (68, 68', 68"; 69, 69', 69") are at an angle with respect to one another or are positioned on top of one another, and can be placed in an operational position in which the two series of pipe sections (68, 68', 68"; 69, 69', 69") extend in the extension of one another,
D.  wherein the first and the second element (41, 42) can be placed in the operational position alongside one another such that the feed and discharge manifolds (43, 44, 45, 46) of the elements extend in the extension of one another in the transverse direction,
E.  wherein the feed and discharge manifolds of the two elements are provided with a coupling member (47, 48) to make a fluid-tight connection between the respective feed and discharge manifolds of the first and the second element.”
16.	Here I must mention one further important aspect of the common general knowledge. The judge found that the whole system shown in figure 8 was common general knowledge with the exception of integer C of claim 1. Although the use of flexible coupling members for joining lengths of longitudinal pipes was known, there was no evidence that these coupling members were sufficiently flexible to permit one length of pipe to flex significantly in relation to an adjacent pipe so that one length could fold back over another.
Priority
17.	The patent claims priority from Netherlands patent application 1,022,998 entitled “Mobile heat exchanger and system for providing a skating rink with such heat exchanger” (“the priority document”). This, like the patent, is directed to an improved heat exchanger for use in a mobile ice rink. It opens with a description of a conventional heat exchanger comprising:
“… at least one assembly of at least two generally rigid pipes for transport of a first medium, and a coupling element which interconnects the two pipes, and feed means and discharge means connected to the assembly for feeding and discharging of the first medium, respectively, the first medium being adapted for heating or cooling of a second medium surrounding the assembly. The invention also relates to an assembly for use in such a mobile heat exchanger. The invention furthermore relates to a system for providing a skating rink having such a mobile heat exchanger.”
18.	Such a structure is illustrated in figure 6 of the priority document (corresponding to figure 7 of the patent):

19.	Here the housing (22) comprises several assemblies (23) of longitudinal pipes (24) which are connected together using coupling elements (25). Feed and discharge manifolds or collectors are connected to each assembly at one end (28) and a transverse connector is connected to each assembly at the other end (27). 
20.	The invention of the priority document is addressed to the disadvantages of known heat exchangers and, like the patent, involves the addition of coupling elements (25) which can “pivot”, “the pipes being connected in such a way to the pivoting coupling element that the pipes can be hinged with respect to one another between an active operating position in which the assembly has a relatively extended configuration and a non-operative transport position wherein the assembly has a relatively compact configuration” (page 1, lines 25 to 29).
21.	It is also explained (at page 3, lines 7 to 19) that the assembly of pipes is not restricted to two pipes (effectively pipe sections) but can be provided with several pipes, as a result of which the assembly can acquire a relatively long length, and in this way make the heat exchanger longer; and that a number of assemblies of pipes may be arranged parallel to one another to make the heat exchanger wider.
22.	This invention is reflected in claim 1 of the priority document which reads:
“Mobile heat exchanger, comprising: 
-	at least one assembly of 
-	at least two generally rigid pipes for transport of a first medium, and 
-	a coupling element which interconnects the two pipes, and
-	feed means and discharge means connected to the assembly for feeding and discharging of the first medium, respectively, the first medium being adapted for heating or cooling of a second medium surrounding the assembly, characterised in that, the coupling element can pivot, the pipes being connected in such a way to the pivoting coupling element that the pipes can be hinged with respect to one another between an active operating position in which the assembly has a relatively extended configuration and a non-operative transport position wherein the assembly has a relatively compact configuration.”
23.	There is, therefore, an important difference between the disclosure of the priority document and that of the patent, and it is the one on which the issue of priority hangs. The priority document does not contain any express disclosure of the multiple elements shown in figure 8 of the patent. As I have explained, figure 8 shows multiple elements (41, 42), each of which has a feed manifold (43, 45) and a discharge manifold (44, 46). These elements are placed alongside one another in such a way that:
i)	the feed and discharge manifolds (43, 44, 45, 46) of the elements “extend in the extension of one another in the transverse direction”, and
ii)	the feed and discharge manifolds of the two elements “are provided with a coupling member (47, 48) to make a fluid-tight connection between the respective feed and discharge manifolds of the first and second element”.
24.	It will be appreciated that the italicised words in the immediately preceding paragraph reflect integers A, D and E of claim 1 of the patent. There is no express disclosure of any of these integers in the priority document.
25.	The deputy judge held that the patent was not entitled to priority. He understood the argument of Ice-World to be that, although there was no express disclosure in the priority document of multiple elements or the way they should be connected together, these features were nevertheless disclosed because the priority document had to be interpreted through the eyes of the notional person skilled in the art and such a person, familiar with the common general knowledge, would understand these features to be present in any ice rink made using the heat exchangers of the priority document.
26.	The deputy judge rejected this argument. He accepted that the priority document has to be interpreted through the eyes of the skilled addressee who is equipped with the common general knowledge but held this does not permit the court to read into the priority document aspects of the common general knowledge which it does not disclose.
27.	Upon this appeal Ice-World has been represented by Mr Daniel Alexander QC, Mr James Tumbridge and Ms Ashton Chantrielle. Mr Alexander submits that the key novel and inventive feature of the invention is integer C, that is to say, the use of joint members (70) which allow the longitudinal pipes to have two configurations, one in which the pipes are extended and the other in which the pipes are folded back on one another. This is the integer which enables the claimed system to work in its intended manner. Integer C is, in substance, the invention.
28.	Mr Alexander continues that the same invention is disclosed in the priority document. All that has been done in the patent is to include an additional diagram showing the invention in use in one kind of common general knowledge set-up, that is to say one in which two elements, placed side-by-side, are connected together in an entirely conventional way. 
29.	The question, says Mr Alexander, is whether, as a matter of substance not form, the skilled person can derive the subject matter of the claim in issue directly and unambiguously, using common general knowledge, from the disclosure of the priority document. The disclosure must also be enabling. A claimed invention is entitled to priority provided it contains the same information about the invention as the priority document, whether that information is in the priority document’s claim, statement of invention or other text or a drawing. Priority is about implicit and explicit technical disclosure. The relevant tribunal has to consider whether the priority document gives the skilled person essentially the same information about the invention which forms the subject of the claim in issue, and whether it does so in such a way as to enable that person to perform the invention in accordance with the claim. The court should not be distracted by immaterial changes in wording so long as those changes do not affect the invention.
30.	Here, Mr Alexander argues, the deputy judge fell into error because he failed to appreciate or take proper account of the fact that integer C, which was accepted to be the invention of the patent, is disclosed in the priority document. Integer E is simply a common general knowledge way of putting it into practice. The priority document states that assemblies can be connected together in a parallel manner to increase the width of the heat exchanger. But it contains no suggestion that the invention can only be used in ice rinks of a particular size, or in ice rinks in which the relevant manifolds are not constructed out of sub-elements in the standard way. So, having accepted that longer lengths of manifolds could, as a matter of common general knowledge, be achieved by joining together individual manifold elements, he ought to have found that the skilled person would understand that the priority document disclosed an invention which was usable in a conventional way.
31.	Mr Douglas Campbell QC has appeared at this appeal on behalf of Icescape, as he did below. He submits that figure 8 and claim 1 of the patent disclose for the first time the use of two elements (feature A) placed alongside each other in the required manner (feature D) with the necessary coupling member (feature E). None of these features is expressly or implicitly disclosed in the priority document. Ice-World’s argument necessarily depends upon the incorporation into the priority document of important aspects of the common general knowledge, and that is not permissible. The deputy judge therefore came to the correct conclusion and he did so for the right reasons.
32.	Assessment of these rival submissions must begin with art.87(1) of the European Patent Convention (the “EPC”) which says: 
“(1) A person who has duly filed in or for any State party to the Paris Convention for the Protection of Industrial Property, an application for a patent or for the registration of a utility model or for a utility certificate or for an inventor's certificate, or his successors in title, shall enjoy, for the purpose of filing a European patent application in respect of the same invention, a right of priority during a period of twelve months from the date of filing of the first application.” 
33.	In decision G2/98 Same Invention, [2001] O.J. EPO 413; [2002] E.P.O.R. 167 the Enlarged Board of Appeal considered the meaning of art.87(1) EPC, and in particular, the meaning of the expression “the same invention”. It did so because of conflicting decisions of the Boards of Appeal. As the Enlarged Board explained, in one line of authority, the traditional line, the scope of the right to claim priority from a previous application was determined by, and limited to, the extent to which the subject matter claimed in the later application had been expressly or at least implicitly disclosed in the earlier application. This principle applied both where the scope of protection in the later application was broader than that in the previous filing, and also where the scope of the protection in the later application was more narrowly defined. Under this line of authority, it was irrelevant whether the previously undisclosed added features were essential elements of the claimed invention or not.
34.	The other line of authority was exemplified by decision T73/88 Snackfood/HOWARD (OJ EPO 1992, 557). Here the priority of a previous filing for a main claim was recognised although the later filing contained a technical feature which was not disclosed in the earlier application. The Enlarged Board held that the added feature did not relate to the function and effect, and hence to the character and nature, of the invention. The absence of such a feature from the disclosure of the priority document did not cause a loss of priority, provided that the claim was otherwise in substance in respect of the same invention as that disclosed in the priority document. Whether a particular feature was essential for the purposes of priority and therefore needed to be disclosed in the priority document depended upon its relationship to the character and nature of the invention. So, for example, in decisions T582/91 and T364/95 the added feature was treated as a voluntary limitation of the scope of the claim which did not represent an essential element of the subject matter of the claim and priority was retained.
35.	The Enlarged Board carried out a thorough analysis of the merits of each approach before concluding that the narrow or strict interpretation of the concept of “the same invention” was necessary to ensure a proper exercise of priority rights in full conformity with the principles of equal treatment of the applicant and third parties and legal certainty, and with the requirement of consistency with regard to the assessment of novelty and inventive step:
“9.  From the analysis under point 8 supra, it follows that an extensive or broad interpretation of the concept of "the same invention" referred to in Article 87(1) EPC, making a distinction between technical features which are related to the function and effect of the invention and technical features which are not, with the possible consequence that a claimed invention is considered to remain the same even though a feature is modified or deleted, or a further feature is added (cf. point 8.3 supra), is inappropriate and prejudicial to a proper exercise of priority rights. Rather, according to that analysis, a narrow or strict interpretation of the concept of "the same invention", equating it to the concept of "the same subject-matter" referred to in Article 87(4) EPC (cf. point 2 supra), is necessary to ensure a proper exercise of priority rights in full conformity inter alia with the principles of equal treatment of the applicant and third parties (cf. point 8.1 supra) and legal certainty (cf. point 8.3 supra) and with the requirement of consistency with regard to the assessment of novelty and inventive step (cf. point 8.1 supra). Such interpretation is solidly supported by the provisions of the Paris Convention (cf. point 5 supra) and the provisions of the EPC (cf. point 6.8 supra), and is perfectly in keeping with opinion G3/93 (cf. point II.(vi) supra). It means that priority of a previous application in respect of a claim in a European patent application in accordance with Article 88 EPC is to be acknowledged only if the person skilled in the art can derive the subject-matter of the claim directly and unambiguously, using common general knowledge, from the previous application as a whole.”
36.	The Enlarged Board then answered the question of law in these terms:
“The requirement for claiming priority of "the same invention", referred to in Article 87(1) EPC, means that priority of a previous application in respect of a claim in a European patent application in accordance with Article 88 EPC is to be acknowledged only if the skilled person can derive the subject-matter of the claim directly and unambiguously, using common general knowledge, from the previous application as a whole.”
37.	It followed that decisions of the Boards of Appeal such as T582/91 and T364/95 were no longer relevant.
38.	The decision of the Enlarged Board in G2/98 has since been considered in a number of decisions of the Court of Appeal.  In Pharmacia Corp v Merck & Co Inc [2002] RPC 41 Aldous LJ, with whom Sedley LJ agreed, explained (at [101]) that the priority document must contain sufficient material for the priority document to constitute the enabling disclosure of the claim in issue. 
39.	In Unilin Beheer NV v Berry Floor NV [2005] FSR 6, Jacob LJ emphasised that the important thing to focus on is whether the priority document as a whole discloses matter which effectively gives the skilled person essentially the same information as that the subject of the claim whose priority is in question:
“48. … The approach is not formulaic: priority is a question about technical disclosure, explicit or implicit. Is there enough in the priority document to give the skilled man essentially the same information as forms the subject of the claim and enables him to work the invention in accordance with that claim?”
40.	A little later he explained that one must look at the disclosure of the priority document as a whole:
“49. … The claims (if any—there is no rule that there should be) of the priority document are not determinative. They are just part of its disclosure. For the purposes of priority one just looks at the disclosure as a whole.”
41.	In Medimmune v Novartis [2012] EWCA Civ 1234, the Court of Appeal referred to Unilin and approved this passage in my decision in Abbott Laboratories Ltd v Evysio Medical Devices plc [2008] EWHC 800 (Pat) in which I added that the priority document must give the skilled person the information the subject of the claim directly and unambiguously:
“228. So the important thing is not the consistory clause or the claims of the priority document but whether the disclosure as a whole is enabling and effectively gives the skilled person what is in the claim whose priority is in question. I would add that it must “give” it directly and unambiguously. It is not sufficient that it may be an obvious development of what is disclosed.”
42.	The priority document is read through the eyes of the skilled person and such a person is of course equipped with the common general knowledge. But this knowledge is used for the purpose of interpreting the disclosure of the priority document and placing it in a context, and not for the purpose of supplementing that disclosure or adding to it what may seem to be a perfectly obvious further feature.  So in HTC Corporation v Gemalto SA [2014] EWCA Civ 1335, Floyd LJ, with whom Vos and Laws LJJ agreed, said this:
“65 The skilled person must be able to derive the subject matter of the claim directly and unambiguously from the disclosure of the priority document. Mr Tappin stressed that the question was one of what was disclosed to the skilled person, not what was made obvious to him by the priority document, for example in the light of his common general knowledge. I agree that, as the above passage shows, that is the correct approach. That does not mean, however, that the priority document should be read in a vacuum. The question of what a document discloses to a skilled person takes account of the knowledge and background of that person. A document may mean one thing to an equity lawyer and another to a computer engineer, because each has a different background. The document still only has one meaning because it is only the relevant skilled person's understanding which is relevant. What is not permissible is to go further than eliciting the explicit or implicit disclosure and take account of what a document might lead a skilled person to do or try, or what it might prompt him to think of.”
43.	In my judgment the application of these principles provides a clear answer to the question before us. I accept that the key novel and inventive feature of the claimed invention is the use of joint elements (70) which enable the folding of the unit to take place. I am also prepared to accept that the skilled person would readily appreciate that one element of the kind depicted in figure 6 of the priority document could be joined to another to increase the width of the ice rink. But that does not alter the fact that there is no express or implicit disclosure in the priority document of two such elements joined together or of features A, D or E of claim 1 of the patent. Nor is it possible to derive these features directly and unambiguously, using common general knowledge, from the priority document as a whole. The skilled person seeking to implement the teaching of the priority document might join two elements together, but equally he might not, for he might have no need to do so. In these circumstances I have no doubt that Mr Alexander is inviting us to take a course which has been closed to us by the decision of the Enlarged Board in decision G2/98. It is not enough to say that features A, D and E do not relate to the function and effect, and hence to the character and nature, of the invention. The claim to priority depends upon the express or implicit disclosure of those features in the priority document and, since there is no such disclosure, the claim to priority must fail.
44.	It follows that the deputy judge came to the right conclusion on this issue. The patent is not entitled to priority and is therefore invalid.
Infringement
45.	Icescape accepted at trial that its mobile ice rink incorporated all of the features of claim 1 of the patent save for features D and E and, in particular, the need for a “coupling member to make a fluid-tight connection between the respective feed and discharge manifolds of the first and the second element”. Before turning to the arguments of the parties, I must explain the structure and mode of operation of Icescape’s system. It is convenient to do this by reference to the flow diagrams below (which form figure 1 of the product description and figure 3 of the judgment):

46.	The system comprises three elements, E1, E2 and E3. Coolant enters the system from the right-hand side through pipe P and flows into the manifold F1. The end member BF provides a stop. The coolant then flows through each of the three pipes F2 to a further manifold F3. From there it passes through a number of parallel longitudinal pipes C (each of which has foldable joints) to a connector which is coloured orange. It then becomes discharge flow, passes down the longitudinal pipes C (each of which has foldable joints, once again) to a discharge manifold D3, through the pipe D2 to the further discharge manifold D1, and then back to the chiller and the pump X.
47.	The deputy judge included as figure 5 to his judgment a photograph which shows three elements E1, E2 and E3 extending side-by-side across the width of the installation:

48.	The deputy judge rejected the infringement claim on the basis that it ignored the language of the claim and involved replacing feature E with either nothing at all or with language such as “wherein the feed and discharge manifolds of the two elements are connected into the system in some leak-free manner”.
49.	Upon this appeal Mr Alexander submits the deputy judge fell into error. He has developed the infringement case in the following way. He argues that each of E1, E2 and E3 contains a feed and a discharge manifold, respectively F3 and D3, connected to the cooling pipes. There is a physical part which, among other things, maintains the feed and discharge elements in that position, and does so detachably. This part is a coupling member and takes the form of an additional manifold (F1, F2, D1, D2) which both (i) makes a fluid tight connection between the manifolds by coupling to them and (ii) keeps them in position. In this way a coupling member makes a fluid tight connection between the respective feed and discharge manifolds of the first and second elements. It is fair to describe this as making a parallel connection between the elements rather than a series connection as shown in the patent specification but that is neither here nor there. Dr Pearson, Ice-World’s expert, produced a diagrammatic representation of this parallel connection which forms figure 6 of the judgment:

50.	Mr Alexander submits that this arrangement satisfies all of the integers of the claim. Figure 5 shows that the elements are placed in an operational position alongside one another so that the feed and discharge manifolds of the elements “extend in the extension of one another” in the transverse direction. This is all that is required to meet integer D of the claim because this integer says nothing about the nature of the flow between the elements. Furthermore, continues Mr Alexander, the feed and discharge manifolds (F3, D3) are provided with a coupling member in the form of an additional manifold which makes a fluid tight connection between the feed and discharge manifolds of the first and the second elements. This meets the requirements of integer E of the claim. 
51.	Mr Alexander has also argued, albeit faintly, that the manifolds (F1 and D1) are 12 metres long and are made up of pipes that are welded together on site. Presumably, Mr Alexander continues, if Icescape wanted to increase the width of its rinks, it could simply weld more sections of pipe together. This is another form of coupling to create a fluid tight connection.
52.	Mr Campbell responds that, so far as the fluid path is concerned, the elements are indeed in parallel and not in series. So, he continues, the incorporation of the secondary manifold means that the coolant only flows through one element rather than through all of them.  E1 receives coolant from F1 and returns it to D1. E2 also receives coolant from F1 and returns it to D1, but this coolant has not been through E1. The same goes for E3. Indeed, the feed lines F2 and discharge lines D2 contain a non-return valve which ensures that coolant can flow only in the intended direction.
53.	This system provides significant advantages, submits Mr Campbell. The cooling elements are independent of each other; they can be tested independently; their flows and discharges can be regulated independently; and individual elements can even be shut down. It also follows that each of the elements receives equally cold coolant rather than one having to make do with coolant which has already been used in another. But Mr Campbell accepts that there is a disadvantage too, namely that the whole assembly is more complicated as a result of the extra piping and will take longer to install and break down, contrary to the purpose of the patent.
54.	Mr Campbell also dismisses the attempt by Mr Alexander to rely upon the F1 and D1 pipes. The problem with this, says Mr Campbell, and I agree, is that, once their various components have been welded together, they become a single manifold, not manifolds provided with a coupling member.
55.	The courts in this country have adopted what has been called a purposive approach to the interpretation of patents since the decision of the House of Lords in Catnic v Hill & Smith [1982] RPC 183. Lord Diplock explained (at pages 242-243) that a patent specification should be given a purposive interpretation rather than a purely literal one derived from a meticulous verbal analysis and that the question in each case is: whether persons with practical knowledge and experience of the kind of work in which the invention was intended to be used, would understand that strict compliance with a particular verb or phrase appearing in a claim was intended by the patentee to be an essential requirement of the invention so that any variant would fall outside the monopoly claimed, even though it could have no material effect upon the way the invention worked.
56.	In Improver v Remington [1990] FSR 181 Hoffmann J (as he then was) analysed the speech of Lord Diplock in Catnic and formulated three questions the court should ask itself in order to determine whether a feature embodied in an alleged infringement which fell outside the primary, literal or acontextual meaning of a descriptive word or phrase in a claim was nevertheless within its language as properly interpreted. These questions, which subsequently became known as the Protocol questions or guidelines, reflecting the Protocol on art.69 EPC, were applied by the courts in appropriate cases in order to arrive at a purposive interpretation of the claims.
57.	The law was reviewed by the House of Lords in Kirin-Amgen v Hoechst Marion Roussel [2005] RPC 9. This decision was given before the Protocol to art.69 was amended by EPC 2000 to introduce art.2, but the terms of the amendment were settled and were before the House of Lords. In very broad summary Lord Hoffmann explained that art.69 EPC and the Protocol were given effect, so far as infringement was concerned, by ss.60 and 125 of the 1977 Act; that purposive construction involved ascertaining what the person skilled in the art would have understood the patentee to be using the language of the claim to mean; that Catnic was precisely in accordance with the Protocol; and that although art.69 prevented any notion of equivalence from extending protection outside the claims, there was no reason why it could not be an important part of the background of facts known to the skilled man which would affect what he understood the claims to mean. The principle of purposive construction therefore gave effect to the requirements of the Protocol. As for the Protocol questions, these were guidelines for applying that principle to equivalents and would be more useful in some cases than in others.
58.	The position remained settled until the decision of the Supreme Court in Actavis UK Ltd v Eli Lilly & Co [2017] UKSC 48, [2017] RPC 21.  Lord Neuberger, with whom the other members of the court agreed, explained (at [54]) that, notwithstanding what Lord Diplock had said in Catnic, a problem of infringement is best addressed by addressing two issues, each of which must be considered through the eyes of the person skilled in the art. They are (i) does the variant infringe any of the claims as a matter of normal interpretation; and, if not, (ii) does the variant nonetheless infringe because it varies from the invention in a way or ways which is or are immaterial? If the answer to either issue is “yes”, there is an infringement; otherwise, there is not. Lord Neuberger continued that this approach complies with art.2 of the Protocol because issue (ii) squarely raises the principle of equivalents, but limits its ambit to those variants which contain immaterial variations from the invention. It complies with art.1 of the Protocol because it involves balancing the competing interests of the patentee and of clarity, and it seeks to balance the encouragement of inventions and their disclosure with the need for a competitive market. Lord Neuberger added that issue (i) self-evidently raises a question of interpretation, whereas issue (ii) raises a question which would normally have to be answered by reference to the facts and expert evidence.
59.	It is, in my view, clear that this approach is markedly different from that which the courts in this country have adopted since Catnic. Any doubt about the matter is resolved by Lord Neuberger’s judgment at [55] where he explained that Lord Hoffmann had effectively conflated the two issues into one single issue of construction. Lord Neuberger continued that he had considerable difficulties with the notion that there was a single conflated, or compound, issue and that, even if this notion were correct, that the issue was one of interpretation. In his view this was wrong in principle and could lead to error.
60.	Lord Neuberger proceeded to elaborate (at [58]) the correct approach to issue (i). It is, he explained, a problem of interpretation to which the applicable principles are tolerably clear and were affirmed by Lord Hodge in Wood v Capita Insurance Services Ltd [2017] UKSC 24, [2017] 2 WLR 1095 at [8] to [15]. But of course patents are different from contracts. Patents are addressed to all persons skilled in the art and describe and claim an invention for the purposes of securing a monopoly. Unlike a contract and as Lord Diplock emphasised in Catnic, a patent is a unilateral statement by the patentee, in words of his own choosing, addressed to persons skilled in the art, by which he informs them what he claims to be the essential features of his invention. Indeed Lord Neuberger himself made clear at [54] that issue (i) must be considered through the eyes of the skilled addressee, and at [56] that issue (ii) involves not merely identifying what the words of the claim would mean in their context to the addressee (in other words, I interpolate, issue (i)), but also considering the extent to which the scope of protection should extend beyond that meaning. So I have no doubt that (despite Lord Neuberger’s use of the term “literal” in considering issue (ii) and to which I will come in a moment) issue (i) involves purposive interpretation. I note this was also the view of Arnold J in Mylan v Yeda [2017] EWHC 2629 (at [138]) and of Carr J in Illumina Inc and ors v Premaitha Health Plc and anor [2017] EWHC 2930 at [201]. But I would add this: the question of equivalence is now addressed in issue (ii), as I will now explain.  
61.	Lord Neuberger considered issue (ii), namely what it is that makes a variant immaterial, from [59] to [65]. He thought that the three questions formulated by Hoffmann J in Improver were helpful but needed some elaboration and, particularly the second question, some reformulation. 
62.	The first Improver question, whether the variant has a material effect on the way the invention works, was addressed by Lord Neuberger at [60]. He thought this was generally satisfactory but the court must focus on “the problem underlying the invention”, “the inventive core”, or the “inventive concept”. In effect the question is whether the variant achieves the same result in substantially the same way as the invention.    
63.	Lord Neuberger considered the second Improver question from [61] to [64]. He considered this was unsatisfactory because it imposed too high a burden on the patentee to ask whether it would have been obvious to the notional addressee that the variant would have no material effect on the way in which the invention worked, given that it required the addressee to figure out for himself whether the variant would work. The second question was better expressed as asking whether, on being told what the variant does, the notional addressee would consider it obvious that it achieved substantially the same result in substantially the same way as the invention. It should therefore be asked on the assumption that the notional addressee knows that the variant works to the extent that it actually does work. This question also applies to variants which rely on, or are based on, developments which have occurred since the priority date. Lord Neuberger left open the question whether or not the variant should not itself be inventive but found it hard to see why that alone should prevent the variant from infringing the original invention.
64.	The third Improver question, namely whether the notional addressee would have understood from the language of the claim that the patentee intended that strict compliance with the primary meaning was an essential requirement of the invention, was considered by Lord Neuberger at [65]. He thought this was acceptable provided it was properly applied. Here he made four points:
i)	Although “the language of the claim is important”, consideration of this question does not exclude the specification of the patent and all the knowledge and expertise which the notional addressee is assumed to have.
ii)	The fact that the language of the claim does not on any sensible reading cover the variant is certainly not enough to justify holding that the patentee does not satisfy the third question.
iii)	It is appropriate to ask whether the component at issue is an “essential” part of the invention, but that that is not the same thing as asking if it is an “essential” part of the overall product or process of which the inventive concept is part. Here regard must be had to the inventive concept or the inventive core of the patent.
iv)	When one is considering a variant which would have been obvious at the date of infringement rather than at the priority date, it is necessary to imbue the notional addressee with rather more information than he might have had at the priority date. Here Lord Neuberger had in mind the assumption that the notional addressee knows that the variant works.
65.	Then, at [66], Lord Neuberger set out the three reformulated questions:
i)	Notwithstanding that it is not within the literal meaning of the relevant claim(s) of the patent, does the variant achieve substantially the same result in substantially the same way as the invention, i.e. the inventive concept revealed by the patent?
ii)	Would it be obvious to the person skilled in the art, reading the patent at the priority date, but knowing that the variant achieves substantially the same result as the invention, that it does so in substantially the same way as the invention? 
iii)	Would such a reader of the patent have concluded that the patentee nonetheless intended that strict compliance with the literal meaning of the relevant claim(s) of the patent was an essential requirement of the invention? 
66.	The whole approach to interpretation and scope of protection therefore involves the following steps, considered through the eyes of the notional addressee:
i)	Does the variant infringe any of the claims as a matter of normal interpretation?
ii)	If not, does the variant nevertheless infringe because it varies from the invention in a way or ways which is or are immaterial? This is to be determined by asking these three questions:
a)	Notwithstanding that it is not within the literal (that is to say, I interpolate, normal) meaning of the relevant claim(s) of the patent, does the variant achieve substantially the same result in substantially the same way as the invention, i.e. the inventive concept revealed by the patent?
b)	Would it be obvious to the person skilled in the art, reading the patent at the priority date, but knowing that the variant achieves substantially the same result as the invention, that it does so in substantially the same way as the invention? 
c)	Would such a reader of the patent have concluded that the patentee nonetheless intended that strict compliance with the literal meaning of the relevant claim(s) of the patent was an essential requirement of the invention?
67.	Of course, in order to establish infringement in a case where there is no infringement as a matter of normal interpretation, a patentee would have to establish that the answer to questions (a) and (b) above is “yes” and that the answer to question (c) is “no”.
68.	There is one further matter I must mention for reasons which will soon become apparent. The Supreme Court also dealt with the effect of the prosecution history. Lord Neuberger referred at [82] to this passage in the speech of Lord Hoffmann in Kirin-Amgen at [35]:
“The courts of the United Kingdom, the Netherlands and Germany certainly discourage, if they do not actually prohibit, use of the patent office file in aid of construction. There are good reasons: the meaning of the patent should not change according to whether or not the person skilled in the art has access to the file and in any case life is too short for the limited assistance which it can provide. It is however frequently impossible to know without access, not merely to the file but to the private thoughts of the patentee and his advisors as well, what the reason was for some apparently inexplicable limitation in the extent of the monopoly claimed.”
69.	Lord Neuberger continued that in the absence of good reasons to the contrary, it would be wrong to depart from what was said by the House of Lords.  Then, after dealing with the position in other important jurisdictions, Lord Neuberger explained the approach to be adopted in these terms: 
“87.  In my judgment, it is appropriate for the UK courts to adopt a sceptical, but not absolutist, attitude to a suggestion that the contents of the prosecution file of a patent should be referred to when considering a question of interpretation or infringement, along substantially the same lines as the German and Dutch courts. It is tempting to exclude the file on the basis that anyone concerned about, or affected by, a patent should be entitled to rely on its contents without searching other records such as the prosecution file, as a matter of both principle and practicality. However, given that the contents of the file are publicly available (by virtue of art.128 EPC 2000) and (at least according to what we were told) are unlikely to be extensive, there will be occasions when justice may fairly be said to require reference to be made to the contents of the file. However, not least in the light of the wording of art.69 EPC 2000, which is discussed above, the circumstances in which a court can rely on the prosecution history to determine the extent of protection or scope of a patent must be limited. 
88.  While it would be arrogant to exclude the existence of any other circumstances, my current view is that reference to the file would only be appropriate where (i) the point at issue is truly unclear if one confines oneself to the specification and claims of the patent, and the contents of the file unambiguously resolve the point, or (ii) it would be contrary to the public interest for the contents of the file to be ignored. The first type of circumstance is, I hope, self-explanatory; the second would be exemplified by a case where the patentee had made it clear to the EPO that he was not seeking to contend that his patent, if granted, would extend its scope to the sort of variant which he now claims infringes.
70.	I turn then to the application of these principles to the circumstances before us in this appeal and I begin with normal, that is to say, purposive, interpretation. I have not found this an easy question to answer but in the end I have come to the conclusion that the deputy judge arrived at the correct conclusion. Integer D calls for the first and second elements to be placed in the operational position alongside one another and this is done in such a way that the feed and discharge manifolds extend in the extension of one another in the transverse direction. Integer E must be read with integer D and requires these feed and discharge manifolds to be joined together by a fluid tight connection. I think the natural reading of these two integers in light of the teaching of the specification and the common general knowledge is that the two manifolds are connected together in series so that the fluid does not leak as it flows between them from one to the other.      
71.	As the Supreme Court has now explained in Actavis, that is not the end of the enquiry, however. It is now necessary to move to issue (ii) and to consider whether the variant differs from the claimed invention in ways which are immaterial. For that purpose I must address Lord Neuberger’s three reformulated questions which I will call the “Actavis questions”.
72.	The first Actavis question requires me to consider whether, notwithstanding that the Icescape system is not within the literal meaning of claim 1, it achieves substantially the same result in substantially the same way as the invention. Here I must have regard to the problem underlying the invention and the patent’s inventive core. I do not think there can be any doubt about the answer to this question. The inventive core of the patent is the provision of the joint member (70). This forms a connection between the rigid pipe sections which is fluid tight and flexible and allows the connected pipe sections to fold relative to one another for the purposes of transportation. It is this feature which makes the patented system different from the conventional systems which formed part of the common general knowledge. By contrast, integers D and E are simply common general knowledge ways of implementing that inventive concept. Focusing on that inventive core, as I must, I am satisfied the variant does achieve the same result in substantially the same way as the invention. It satisfies the aims of the patent, namely to provide a cooling member which can be installed rapidly and is reliable in operation, with which it is possible to proceed rapidly to the ice-forming stage, and with which a mobile ice rink can be made with a large number of different surface areas. It is true that the Icescape system has a parallel rather than a series connection between the manifolds and that this may itself confer certain advantages but also carry with it certain disadvantages, as I have explained at [53] above. But this has nothing to do with the inventive core of the patent. I would therefore answer the first Actavis question in the affirmative.
73.	The second Actavis question is whether it would be obvious to the person skilled in the art, reading the patent and knowing that the variant achieves substantially the same result as the invention, that it does so in substantially the same way as the invention. I would answer this question in the affirmative too. In my judgment it would be entirely obvious to the skilled person that, so far as the inventive core of the patent is concerned, the Icescape system achieves substantially the same result as the invention and does so in substantially the same way. Indeed it does so in precisely the same way.
74.	That leaves the third Actavis question: would the skilled reader of the patent have concluded that Ice-World nonetheless intended that strict compliance with the literal meaning of the claim and, in particular, features D and E, was an essential requirement of the invention? Here I must have in mind that the fact that the language of the claim does not cover the variant is certainly not enough to justify holding that Icescape does not satisfy this question. I must also consider whether integers D and E are an essential part of the invention and here must have regard once again to the inventive concept and inventive core of the patent. In my judgment the answer to this question is plainly “no”. There is no reason why the skilled reader would have thought that strict compliance with integers D and E was an essential requirement of the invention. The inventive core of the patent has nothing to do with the coupling of the elements together or whether the fluid flows through them in series or in parallel.
75.	The infringement case at trial was argued and decided before the decision of the Supreme Court in Actavis and Mr Alexander has frankly accepted that it was not advanced on an Improver basis. I have therefore considered anxiously whether Ice-World should be permitted to advance a case of infringement on the basis that the Icescape system varies from the invention in ways which are immaterial. In the end I have decided that it should because all of the necessary evidence was before the court and it cannot be said that the failure by Ice-World to advance the case at trial has caused Icescape any material prejudice.
76.	One matter remains. Mr Campbell says that if Ice-World is permitted to run a case based upon equivalents then Icescape should be permitted to rely upon the prosecution history of the patent. There is force in that point so at the hearing of the appeal we indicated we were prepared to consider, de bene esse, those parts of the prosecution file upon which Icescape wished to rely.
77.	Here Mr Campbell took us to a letter dated 27 May 2008 from the Examining Division of the EPO to the patent attorney acting for Ice-World. In that letter the Examining Division raised a number of objections to various claims of the application, including an objection of lack of novelty to claim 7. This claim was directed to, in effect, a system of longitudinal pipes comprising pipe sections joined together in a fluid tight manner with flexible connectors suitable for use in a cooling member according to claim 1. The Examining Division took the view that this claim lacked novelty in light of earlier patent application GB 2,051,340 A which described a solar heat collection structure which could be collapsed for transport and storage. Ice-World responded to this objection by deleting the claim and proceeding with a claim set directed to a cooling member for a mobile ice rink having all of the features of what became claim 1 of the patent.    
78.	Founding himself on this exchange, Mr Campbell submits that Ice-World deliberately limited the scope of protection to a cooling member having all of the features of claim 1, including features D and E, and so it cannot assert now that features D and E are an inessential part of the invention.
79.	In my judgment this argument has no merit. It is impossible to determine whether the objection raised by the Examiner was a sound one or whether it was necessary to delete claim 7 to meet the objection. More importantly, it is impossible to discern in the correspondence any suggestion that Ice-World was surrendering an ability to argue that features D and E were inessential or that Ice-World was accepting that the scope of the claims did not extend to a system in which the feed and discharge manifolds were connected in parallel rather than in series. The correspondence falls well below the threshold set by the Supreme Court in Actavis. The contents of the file do not unambiguously resolve the point with which we have to deal as to the scope of protection conferred by claim 1 of the patent, and it would not be contrary to the public interest for the contents of the file to be ignored. In my view this is a very good illustration of why it is generally so unprofitable to explore the prosecution history.  
80.	I have therefore reached a different conclusion from that of the deputy judge on the issue of infringement. In my judgment the Icescape system does fall within the scope of protection of claim 1 of the patent.
Threats
81.	It will be recalled that in May 2016 Ice-World sent letters to a number of Icescape’s customers. The deputy judge found and declared in his order that these letters, dated 9 May 2016, constituted actionable threats of patent infringement. They were written by Mr Bottema, the third defendant to the proceedings and the Managing Director of Ice-World.
82.	Mr Alexander does not challenge the finding of the deputy judge that these letters constituted threats but maintains that the deputy judge fell into error in failing to find that Ice-World had a defence to the claim in respect of them which is provided by s.70(2A) of the 1977 Act.  Section 70 has since been amended by the Intellectual Property (Unjustified Threats) Act 2017 but it is agreed that s.70(2A) continues to apply to the threats in issue in these proceedings.
83.	Section 70(2A) reads as follows:
“(2A)    If the defendant or defender proves that the acts in respect of which proceedings were threatened constitute or, if done, would constitute an infringement of a patent—
(a)     the claimant or pursuer shall be entitled to the relief claimed only if he shows that the patent alleged to be infringed is invalid in a relevant respect;
(b)     even if the claimant or pursuer does show that the patent is invalid in a relevant respect, he shall not be entitled to the relief claimed if the defendant or defender proves that at the time of making the threats he did not know, and had no reason to suspect, that the patent was invalid in that respect.”
84.	The deputy judge found that the case on infringement failed and that the patent was invalid. So the question whether Ice-World could satisfy the requirements of s.70(2A)(b) did not need to be answered. The deputy judge nevertheless addressed it in case he was wrong on the issue of infringement. The position now is that, in my judgment, the acts the subject of the threats did constitute an infringement but the judge was right to find that the patent was invalid. So the correctness of the deputy judge’s finding in relation to s.70(2A)(b) is of considerable importance. 
85.	Ice-World relied for the purpose of this defence upon advice which it had received from Mr Jan Walaski of Venner Shipley LLP by letter dated 19 April 2016. Mr Walaski said in that letter that in his opinion the patent was valid and had been infringed by Icescape. The deputy judge was invited to infer from this that in May 2016 Ice-World did not know and had no reason to suspect that the patent was invalid in any relevant respect.   
86.	The deputy judge declined that invitation. There were, he thought, two problems:  
“65.  … The first is that I was not provided with the instructions upon which Mr Walaski based his opinion. Moreover it appears that Mr Walaski did not consider priority at all, basing his opinion entirely on a prior art search he conducted in the context of novelty and inventiveness. In these circumstances, Mr Walaski’s opinion appears to have no value at all.
66.  The second problem is that the person responsible for sending the letters did not condescend to reveal whether or not he knew or suspected that the patent was invalid in any material respect. In circumstances where a party chooses not to lead evidence about the state of mind of a particular individual where that state of mind might be highly relevant and there is no explanation offered, the court will be slow to infer a state of mind in his favour. Indeed, it is hard to conceive of a state of affairs where it would do so, there being no reason for it.”
87.	Mr Alexander submits the judge fell into error for the following reasons. The patent had survived examination in the EPO some 12 years previously. Further, in earlier correspondence neither Icescape nor its patent attorney, Greaves Brewster, had raised the possibility that the priority claim might be defective. Unless there was some reason to suppose that Ice-World had reason to suspect the patent was invalid for that reason, which there was not, there was no reason for anyone, including all of the directing minds of Ice-World, to consider the matter. As it was, it was not until Ice-World received a letter from Clarke Willmott, the solicitors for Icescape, dated 27 May 2016, that it was alerted to the priority issue.
88.	I am not persuaded by these submissions. As Mr Campbell has emphasised, the invalidity of the patent is due to a combination of two matters: first, Ice-World filed a patent application which was not entitled to priority; and secondly, Ice-World made prior public use of the invention during the winter of 2003-2004 at various locations in Belgium, France, Netherlands, Germany and Portugal. In these circumstances it might be thought Ice-World would have great difficulty establishing it had no reason to suspect the patent was invalid. However, the position is, in my judgment, still worse. As the deputy judge explained, he was provided with no information about the knowledge or understanding of the directing minds of Ice-World. Neither Mr Bottema nor anyone else gave evidence on its behalf, and no explanation was provided for Ice-World’s failure to call any such evidence. The basis of the defence rests, in substance, upon the letter of advice given by Mr Walaski. It is true that Mr Walaski said at the start of his letter that he had been instructed to provide an opinion as to the validity of the patent but the deputy judge was given no details of the instructions Mr Walaski was given, and he was provided with no explanation from Mr Walaski or anyone else as to why Mr Walaski did not consider the issue of priority.  
89.	In all these circumstances I am satisfied the deputy judge was entitled and right to find that Ice-World had failed to make good the defence under s.70(2A) of the 1977 Act.
Conclusion
90.	I have come to a different conclusion from that of the deputy judge on the issue of infringement. Nevertheless, the deputy judge was right to find the patent was not entitled to priority and was therefore invalid. The deputy judge was also entitled and right to find that Ice-World had failed to make good a defence to the claim for groundless threats of patent infringement under s.70(2A) of the 1977 Act. I would therefore dismiss this appeal.  
Lord Justice Floyd:
91.	I agree with Lord Kitchin on each of the three issues of priority, infringement and the defence under section 70(2A) of the Patents Act 1977, and therefore that the appeal must be dismissed.  As it is the first time we have had to consider in any depth the effect of the decision of the Supreme Court in Actavis v Lilly (cited by Lord Kitchin at paragraph 58 above), I wish to add a few words of my own.
92.	Article 69(1) of the European Patent Convention provides:
“The extent of the protection conferred by a European patent … shall be determined by the claims.  Nevertheless, the description and drawings shall be used to interpret the claims.”
93.	One would be forgiven for thinking that Article 69 was proposing a purely interpretative approach to determining the scope of protection.  At least on a first reading, Article 69 appears to say that the claims determine the scope of protection, subject to their proper contextual interpretation.  Article 69 was however further explained in the Protocol on its Interpretation.  Article 1 of the Protocol provided;
“Article 69 should not be interpreted as meaning that the extent of the protection conferred by a European patent is to be understood as that defined by the strict, literal meaning of the wording used in the claims, the description and drawings being employed only for the purpose of resolving an ambiguity found in the claims. Nor should it be taken to mean that the claims serve only as a guideline and that the actual protection conferred may extend to what, from a consideration of the description and drawings by a person skilled in the art, the patent proprietor has contemplated. On the contrary, it is to be interpreted as defining a position between these extremes which combines a fair protection for the patent proprietor with a reasonable degree of legal certainty for third parties.”
94.	Two extreme approaches were rejected by the Protocol. The first was one where the strict literal wording of the claims had to be adopted, subject only to an exception where the claims were ambiguous and resort could be had to the description and drawings to resolve it.  The second was one where the claims were a mere guideline, with the protection extending to anything which the description and drawings tells one the patentee has contemplated.  The approach mandated by the Protocol was one “between these extremes” which combines a fair protection for the patent proprietor with a reasonable degree of legal certainty for third parties. 
95.	Until the decision in Actavis the approach adopted by the courts in this country was to regard “purposive construction” as representing the approach mandated by the Protocol.  It was an interpretative approach of the kind suggested by Article 69.  It took account of equivalents, as Lord Hoffmann explained in Kirin Amgen (cited by Lord Kitchin at paragraph 57 above) at paragraph 49, because equivalence can be an important part of the background known to the skilled person which affects what he understands the claim to mean.  
96.	It is now clear from the Supreme Court’s decision in Actavis that purposive construction forms but the first stage in the determination of the scope of protection conferred by the claims. In a sense, the first extreme referred to in Article 1 of the Protocol has been replaced by purposive construction, because it now represents the minimum protection afforded by the patent.  There is a second, non-interpretative exercise which allows the patentee a degree of protection outside the normal, purposive meaning of the claims where the variant from the claim achieves substantially the same effect in substantially the same way.  
97.	It should not be thought, however, that the claims do not continue to have an important function.  It is variants from the claim which have to achieve substantially the same effect in substantially same way as the invention.  The claims remain the starting point for the subsequent analysis of variants. Although we may have edged closer to it, the new approach does not transgress the second of the outlawed approaches in the Protocol, which treats the claim merely as a somewhat vague guideline.  
98.	Although a number of issues remain unresolved, such as the approach the court must take to the scope of protection when considering validity as opposed to infringement, and the approach to inventive variants, the application of these new principles does not create any difficulty in the present case.   As Lord Kitchin has explained, on a purposive interpretation of the patent, the claims must be taken to be limited to a “series” connection between the adjacent “elements”. Nevertheless, a “parallel” connection is an alternative way of implementing multiple elements, and the difference from the claimed means of connection has nothing whatever to do with the core inventive contribution of the patent.  There is nothing to suggest that the patentee regarded series connection as essential in any relevant sense, given that the language of the claim alone is not to be taken to be sufficient to give rise to this inference.  It follows that, had the patent been valid, a finding of infringement would have followed. 
Lord Justice Longmore:
99.	I agree with both judgments.