Blue Gentian LLC & Anor v Tristar Products (UK) Ltd & Anor

This appeal concerns an invention for an expandable garden water hose. The defendants (together “Tristar”) appeal against the judgment of Birss J dated 20 December 2013 and his consequential order in which he found and declared that their garden hose called the FlexAble Hose infringed UK Patent No 2 490 276 (“the patent”) which is owned by the respondents (together “Blue Gentian”). The patent was filed on 26 July 2012, has a priority date of 4 November 2011 and was granted on 1 May 2013.

At trial the only claims of the patent in issue were the main product claim, claim 1, and the method claim, claim 14. Blue Gentian alleged and Tristar accepted that Tristar’s activities in relation to the FlexAble Hose fell within the scope of both claims. Their defence to the action and the basis of their counterclaim was that the patent was invalid because it lacked novelty or was obvious in the light of two prior art publications, namely US Patent Application no. 2003/0000530 A1 (“McDonald”) and US Patent Application no. 2003/0098084 A1 (“Ragner”). The judge rejected all of these contentions. Upon this appeal Tristar argue that the judge fell into error in rejecting the obviousness attacks. They do not appeal against the judge’s findings in relation to lack of novelty.

Tristar recognise that the issue of whether an invention was obvious is a kind of jury question which involves a multi-factorial evaluation by the trial judge of the evidence. They also acknowledge that an appeal court is therefore reluctant to interfere with the decision to which the judge has come unless he or she has erred in principle. However, they argue that the judge has indeed fallen into fundamental error in approaching the allegations of obviousness in this case in that:

The specification begins with a description of the background of the invention. It explains that conventional garden hoses made of resilient flexible materials suffer from a number of well known problems, namely they have to be stored on a reel or in a container, they are relatively heavy and they have a tendency to kink. For this reason, the specification continues, it would be a great benefit to have a hose that is light in weight, contractible in length and kink resistant.

There follows a summary of the invention. In broad terms, it provides a hose which comprises an elastic inner tube inside a non-elastic outer tube. When the hose is connected to a pressurised water supply, the elastic inner tube stretches and expands due to the force created by the pressure differential between the interior and exterior of the hose; then, when the supply is turned off, the inner tube contracts due to the spring force exerted by the stretched material. The separate outer non-elastic tube controls and constrains the expansion of the inner tube. The outer tube and the inner tube are only connected together at their ends.

Various preferred embodiments are then described and illustrated. Specifically, figures 6 and 9 show an embodiment of the invention in its unexpanded form and figures 5 and 10 show that same embodiment in its expanded form:

The judge described how this embodiment works in the following terms at paragraph [24]:

“In the unexpanded state, when not connected to water pressure, the inner tube is in a relaxed condition. There are no forces being applied to expand or stretch it. It has a relatively narrow diameter. In this state the outer tube is ruffled. When the hose is connected to a water supply and the supply turned on, water pressure expands the rubber inner tube. The inner tube will expand laterally (also referred to as radially or circumferentially) and will also expand axially (i.e. along the length of the hose). As the inner tube expands the wall thickness of the inner tube material reduces, in other words the material gets thinner. The radial expansion is constrained by the diameter of the outer tube. The axial expansion is constrained by the length of the outer tube. As the water inflates the inner tube, the hose expands lengthways and the ruffles of the outer tube unfurl until it is smooth (see fig 10). In this state the hose can be used. The hose contains a flow restrictor, which can be a small disc with a narrower bore than the bore of the hose.”

The benefits of this invention are, according to the specification, rather striking. It says that a preferred embodiment is, in its expanded state, 50 feet (15.24m) long but, in its contracted state, only a fifth of that length. It weighs less than two pounds (0.9072kg). In contrast, a conventional rubber hose with a length of 50 feet can weigh up to 12 pounds (5.443kg). Further, the fact that the outer tube can move freely with respect to the inner tube along the entire length of the hose enables the outer tube to become folded, compressed and tightly gathered around the outside of the circumference of the inner tube along its length in its contracted condition. This prevents the hose from kinking and becoming entangled and means it can be stored easily in a small space.

Blue Gentian make and sell a commercial embodiment of the invention under the name X-Hose. We were provided with a sample of this hose during the course of the appeal hearing and on a simple inspection the advantages of the invention were readily apparent.

The parties have helpfully agreed that on this appeal we need only address claim 1 of the patent. It reads as follows (when broken down into its various features):

A garden water hose assembly comprising:

an outer tube formed from a non-elastic and flexible material and no metal;

an inner tube constructed from an elastic material,

said outer tube and said inner tube each having a first end attached together by a first coupler and a second end attached together by a second coupler;

said outer tube being unattached from said inner tube between said first and second couplers;

said outer tube and said inner tube having a substantially shortened first length in a non-water flow contracted state with said outer tube extending about an outer surface of said inner tube in an undulating state and

[said outer tube and said inner tube having] a substantially longer second length with said outer tube capturing said inner tube in an expandedstate upon the application of water pressure to the interior of the elastic inner tube as water flows through the assembly

said inner tube having a larger wall thickness in the contracted state than in the expanded state and the wall thickness decreasing as the hose moves from the contracted to the expanded state, and

wherein a water flow restrictor is provided in or is connected to the second coupler.”

The claim presents no particular difficulties of interpretation. It includes all assemblies which have all the features of the claim and which a skilled person would sensibly call a garden water hose. It must have an outer tube which is non-elastic but flexible and has no metal (feature (b)) and an inner tube which is made from an elastic material (feature (c)). The outer tube and inner tube are attached to each other at their respective ends by first and second couplers (feature (d)) but not in between the ends (feature (e)). These tubes have a substantially shortened first length in a non-water flow contracted state in which the outer tube extends around the outer surface of the inner tube in an undulating state - referred to by the judge as a “ruffled” state - (feature (f)), and a longer second length upon the application of water pressure to the interior of the elastic inner tube (feature (g)). Inevitably, the inner tube becomes thinner as the hose assembly expands (feature (h)). Finally, there must be a water flow restrictor in or connected to the second coupler (feature (i)). The specification explains at paragraph [0051] that this flow restrictor may be a device within the second coupler or a hose nozzle, sprayer or any other device which restricts the flow of liquid within the hose.

Ragner describes pressure-actuated retractable or extendable hoses that can be used to carry any fluid and which axially extend and retract by making use of the force created by the pressure differential between the interior and exterior of the hose and a counteracting biasing means applied to the hose. When designed to carry liquid, hoses of this invention have two basic states, namely an extended state when they are being used, and a retracted state when they are not. In all cases extension and retraction is controlled by adjusting the pressure within the hose against the biasing means. Ragner explains that the biasing means may comprise a spring positioned along the length of the hose, both to support the hose radially, and longitudinally to bias the hose against the pressure (whether above or below the ambient pressure) within the hose.

Attention was naturally focused at the trial upon the description in Ragner of a garden water hose, as illustrated in figures 1A and 1B:

It can be seen that the hose body (30) is attached to a sprinkler head (24). Ragner explains that the hose body can be made with a thin-walled flexible material and that the connectors (20) and (22) can be made to match standard garden hose connectors. It continues that almost all water nozzles and sprinklers provide significant restrictions to the flow of water and so to increase the pressure within the hose sufficiently to cause it to extend, as shown in figure 1B.

The detailed construction of the hose is illustrated in figure 3A:

Here the biasing means takes the form of a spring (36) and, in the case of the water hose, is biased towards the retracted state. The spring is shown covered with a hose cover material (32) on the outside and a further hose cover material (34) on the inside which together provide a flexible body for the hose. It is suggested these covers may be made of vinyls or other polymers and so can be made thin, but also strong and durable. The inner cover (34) provides most of the pressure holding ability of the hose. The outer cover (32) provides a cover for the spring and also helps to hold the inner cover (34) in place on the spring coils. This outer cover (32) can be eliminated if the cover material (34) is moulded around the spring coils such that it maintains its position on the spring. Alternatively, so it is said, the spring may slide freely with the respect to the hose material. Reverting to the spring (36), the specification teaches that this may be inside, outside or in between the cover materials and may be attached to them or left unattached, save at the hose ends.

Figure 4 shows the behaviour of the hose under pressure:

This is described in the specification at [0060] to [0062]. This passage is one upon which Tristar place particular reliance and so I should set it out in full:

“[0060] FIG. 4 shows a graph of the different pressure states for the disclosed linearly retractable hose. For the discussion of the graph in FIG. 4, the term "longitudinal bias force" or simply "bias force" is defined to include both the spring bias and any biasing caused by the flexible cover material that actually makes up the hose. In most designs the biasing of the flexible cover material of the hose is designed to be small compared to the biasing caused by the spring. However, in some designs, for special purposes, the cover material may represent a significant portion of the bias force. In fact, if desired, the hose may obtain all its biasing force from the cover material, and not need a separate metal or composite spring at all.

[0061] In FIG. 4, when the interior pressure and exterior pressure of the hose are the same (zero gauge pressure), the hose is in what is called its "natural state", where the spring bias determines whether the hose is extended or retracted. This zero gauge pressure is signified by "0 ambient pressure" at the middle of the graph. Pressures to the left of "0" are vacuum pressure (pressure less-than ambient) and pressures to the right of "0" have positive pressure (pressure greater-than ambient). In general, a pressure hose will only experience pressure values to the right of "0" and vacuum hoses will only experience pressures to the left of "0". However, in some applications, pressure fluctuations may extend outside this range for each type of hose.

[0062] As pressures within the hose change, the state or mode that the hose is in, also changes. Reading from left to right on the graph in FIG. 4, [description re vacuum hose omitted] The pressure hose remains retracted until pressure within the hose increases to gauge pressure P₁. At a pressure of P₁ the pressure hose is still fully retracted (net longitudinal force negative, trying to retract hose), but the force exerted by the bias force exactly cancels the force exerted by the internal pressure P₁. As the hose gauge pressure increases from P₁ to P₂, the pressure hose extends and reaches its full length at a pressure of P₂. Again, if fluid is flowing through the hose, restrictions in the hose (fluid friction) may result in significant differences in pressure at different sections of the hose. At the pressure of P₂ the bias force still exactly matches the pressure force (net longitudinal force equals zero), but it can be now fully extended. Above pressure P₂ (net longitudinal force positive-tending to extend hose) the pressure hose remains fully extended and cannot extend significantly further because it is restrained by the hose cover material itself. Thus, the hose maintains substantially its fully extended length between pressure P₂ and up to its "Max. pressure" which is the maximum pressure the hose can withstand.”

A number of points emerge from this text. First, Ragner clearly contemplates that in most cases the biasing force will be provided by or mainly by the spring. But, as the judge noted, the reader can see that Ragner has at least contemplated the idea of something other than a spring being the biasing means. Second, when the axial force generated by the fluid pressure inside the hose exceeds the axial biasing force from the biasing means, the hose extends to its fully extended state where it “cannot extend significantly further because it is restrained by the hose cover material itself”. Thus, Tristar emphasises, Ragner teaches that, to have a maximum length, the hose must have a non-elastic component which prevents further expansion.

I should also draw attention to paragraph [107] of Ragner in which it is explained once again that the spring need not necessarily be made of metal. Specifically, it says:

“In addition, many types and styles of biasing springs can be used for the hose design. For example, plastic or composite materials can be used for the spring. Even the hose cover material itself can be used as the biasing means if made of a resilient material that provides a consistent restoring force. The biasing spring(s) can also be placed on the interior or exterior of the hose. Even elastic bands can be used to bias a linearly retractable hose.”

There is therefore some teaching that the resilient material may be elastic, indeed it may even comprise elastic bands.

Tristar accept, at least for the purposes of this appeal, that Ragner does not disclose, explicitly or implicitly, a product falling within claim 1 of the patent. The judge found and they accept that there is no disclosure of the required combination, the key difference being that Ragner does not describe the combination of an elastic inner tube and a non-elastic outer tube. However, they do contend that it was obvious to produce a hose falling within the scope of claim 1 of the patent and that the judge fell into error in failing so to find.

The judge heard a good deal of evidence on this issue. Mr Sinclair, Blue Gentian’s expert, expressed the view that it would not have been obvious to replace the spring of Ragner with a resilient material because the spring’s function was not only to act as the biasing means but also as the support structure for the cover material. Mr Howe, Tristar’s expert, maintained that it would have been plain to the skilled person that the elasticity required for elongation and retraction of the hose could be achieved without a coiled spring, and that it would have been obvious to make the internal layer from an elastomeric cover material and combine it with a constraining outer layer. Further, Mr Howe continued, to operate correctly, the inner and outer layers would need to be at least partially unbonded along their length.

In the end, the judge preferred the evidence of Mr Sinclair. The heart of his reasoning is set out at paragraphs [60] to [62]:

“60.

The skilled person would be interested in Ragner since it is concerned at least in part with garden hoses. The main disclosure of Ragner is a spring based hose extendable and retractable hose. The reader would see the two references to the cover material providing the biasing force in paragraph [0060] and [0107]. The skilled person would not dismiss these passages and would consider them. They might think that using an elastomeric material as the cover material was an idea worth considering further. However there is nothing in Ragner itself which teaches that two distinct cover materials would need to be used in that context.

61.

The function of the outer cover material 32 disclosed in the document is to cover the spring and hold inner cover 34 in place on the coils. If there is no spring, there is no need for the outer cover material. With hindsight knowledge of the invention we can see that replacing the spring with an elastomeric cover material might create a problem because there will be nothing to restrain the radial expansion of the inner tube. However I do not think it would be obvious to employ a second, inelastic cover material outside the putative elastic inner material to restrain its radial expansion. The function of that outer layer would be different from the outer cover in Ragner.

62.

Moreover it seems to me to involve a further element of hindsight to combine into this reasoning the aspect of paragraph [0057] which discloses an alternative design in which the spring can slide freely with respect to the hose material. The disclosure of sliding freely is the basis for the argument that Ragner implicitly discloses the idea of using two cover materials which are not bonded together along their length. However this teaching about sliding freely and the necessary implication of it has nothing to do with taking forward the reference to using the cover material as the biasing means. They are not linked by Ragner and I see no reason why it was obvious to link them.”

On this appeal Mr Roger Wyand QC and Mr Jonathan Hill have appeared on behalf of Tristar, as they did below. Mr Wyand submits that the judge misconstrued Ragner in that he failed properly to appreciate or take into account the following matters: first, all of the hoses embodying Ragner’s invention have defined minimum and maximum lengths; second, the outer cover material does provide the support which prevents expansion of the hose beyond its defined maximum length; and third, Ragner nowhere teaches the reader to do without a non-elastic cover material if an elastic cover material is used as the biasing means.

Mr Wyand has developed these submissions in the following way. So far as the first point is concerned, he argues that the judge simply does not mention the important feature of all the hoses described in Ragner, namely that they have a maximum, fully extended length. This, he says, directly points to the need to have two cover materials, because a hose which comprises a single elastic cover material cannot have a maximum length. Accordingly, he continues, the skilled person would be bound to appreciate that a non-elastic cover material is essential.

Turning to his second point, Mr Wyand submits that Ragner’s cover material (34) is described as the inner cover material, but the document also makes it clear that the outer cover material (32) is not required. Further, it teaches that the spring can be inside the cover material. Accordingly, he submits, it would be apparent to the skilled person that Ragner does describe a configuration in which the cover material providing the pressure support at maximum extension is on the outside of the hose.

In developing his third point, Mr Wyand submits that the judge omits to mention or take into consideration that there is no suggestion anywhere in Ragner that the skilled person can do without a non-elastic cover material if implementing the invention in such a way that another cover material is used as the biasing means. It is, he says, obvious that the non-elastic cover material is required, not just to prevent over extension in the axial direction but also in the radial direction. Without the non-elastic cover material, when the hose reaches its maximum length, there is a risk (the size of which will depend upon the water pressure) that the hose will bulge and rupture.

Drawing these points together, Mr Wyand contends that the judge was therefore wrong to say, as he did, that “there is nothing in Ragner itself which teaches that two distinct cover materials would need to be used” when implementing the suggestion that the cover material could be used in place of the spring; and further in saying as he did that, if there is no spring, “there is no need for the outer cover material”. Overall, submits Mr Wyand, the combination of an elastic inner tube with a non-elastic outer tube was indeed obvious. The only other difference, that of only attaching the tubes together at their ends, would immediately occur to the skilled person both because this feature is required to enable the two tubes to work in combination and further, because Ragner itself puts the idea of such a construction firmly in the mind of the reader.

Attractively though these submissions have been developed, I find myself unable to accept them. I have reached that conclusion for the following reasons. First, it is I think important to have in mind that, as Mr Howe accepted and the judge recorded, the claimed garden water hose assembly of the patent is an improvement on known garden hoses in that it is light in weight and contractible and therefore easier to store, and kink resistant. These are significant and real advantages. In such a case it seems to me that it is particularly important to avoid hindsight in considering an allegation of obviousness because it is all too easy to say, after the event, that the invention was obvious and could have been arrived at by a series of apparently easy steps.

Second, the focus of Ragner is the provision of a linearly extendable and retractable hose with the general structure shown in figure 3A. This structure has at its heart the biasing spring (36). Depending upon the environment in which the hose is to be used, this spring biases the hose towards extension or retraction and, as the specification goes on to explain, may be integrated into the body of the hose or may be internal or external to it. But however it is arranged, the spring is described as co-operating with the cover materials. Thus the cover (34) is described as providing most of the pressure support and the cover (32) is described as holding the entire system together. When implemented as a garden hose and in its expanded case, the spring (36) acts as a support structure for the hose cover material (34) to keep it from expanding radially too far. As the hose contracts, the materials (32) and (34) bow outwardly in between the coils of the spring (36). This slight outward bowing helps to keep the cover material from getting trapped in between adjacent coils. Further, if the cover (34) is moulded around the spring coils so as to maintain its position in relation to the spring, the cover material (32) can be eliminated.

In the light of this disclosure it seems to me that the judge was fully entitled to attach weight to Mr Sinclair’s opinion that the skilled person would consider that replacing the spring with a resilient material as the biasing means was not in fact a feasible option. He considered, entirely reasonably in my view, that Ragner teaches that the spring’s function is not only to act as a biasing means but also as a support structure.

Third, Ragner certainly does say that, in some designs, for special purposes, the cover material may represent a significant portion of the biasing force and that, if desired, the hose may obtain all its biasing force from the cover material and not need a separate metal or composite spring at all. However, Ragner does not explain how such designs are to be implemented and does not disclose the use of a non-elastic outer cover in this context. In these circumstances I believe that the judge was perfectly entitled to say as he did that Ragner describes the function of the outer cover material (32) as being to cover the spring and hold the inner cover (34) in place on the coil. Accordingly, if there is no spring, there is no need for the outer cover material. It may be perfectly clear now, in light of the patent and the X-Hose that, with a highly elastic inner, it is necessary to have a non-elastic cover material, but that is simply not described in Ragner.

Fourth, an essential feature of the device of the patent is that the inner tube and the outer tube are only connected at their ends. This allows the outer tube to become ruffled (adopting the judge’s expression), as the hose contracts. The structure depicted in figure 3A of Ragner is very different indeed. As the hose expands and contracts, both covers move together. I think the judge was therefore entitled to conclude as he did that it was not obvious to have the two covers sliding freely relative to each other in an embodiment in which one cover acts as the biasing means. Put shortly, Ragner appears to have missed the simple and highly effective structure disclosed in the patent.

For all of these reasons, I would dismiss Tristar’s appeal in relation to Ragner.

McDonald is a short patent application which describes a self-elongating oxygen hose for use on an aircraft. The specification begins with a discussion of the background of the invention in which it is explained that there is a need in the commercial aviation industry for masks that can be donned in a matter of seconds in an emergency. The invention is then summarised and is said to provide supplemental gas assemblies including a mask adapted to fit over at least the nose and mouth of the wearer, and a flexible hose coupled with the mask and a source of gas; in which at least a portion of the mask and the hose are received within a stowage box. The hose assembly comprises a length-expandable hose which, when a user grasps the mask and pulls it from the stowage box, inflates and axially expands. In this way, the stowage requirements for the hose assembly are reduced, or alternatively a hose having a substantially longer effective length can be used in a standard stowage box.

The specification continues at paragraph [0009] with a summary of the hose assembly of the invention. It is said to include an inflatable elastomeric inner tube together with an exterior sheath formed of woven or braided material which in use restricts the radial expansion of the inner tube upon pressurisation, while allowing the tube to expand axially. The hose assemblies are said to have a deployed length of at least 1.5 times their relaxed length. The invention is further described by reference to figures 1 to 3:

As the judge explained, figure 1 shows the arrangement with the hose stowed in a box. It has a hinged cover (44). In the event of cabin depressurisation, the pilot grasps the mask and pulls it up. This causes the hinge cover to open and allows easy removal of the mask. The pilot then pulls the mask to his or her face. During mask deployment, the hose assembly self-elongates from a relaxed condition into a fully extended condition. The hose assembly is described further in paragraphs [0015] and [0016]. This is a part of the application upon which Tristar have placed particular reliance and it reads:

“[0015] The hose assembly 14 is best illustrated in FIGS. 2 and 3 and is designed so that the end thereof remote from mask 12 may be coupled witha conventional connector within box 16. The assembly 14 includes an inner, resilient, expandable tube 30 secured to endmost threaded hose fittings 32 and 34, together with an outer sheath 36 formed of woven or braided material. The sheath 36 is secured to the ends of the hose assembly by means of crimp ferrules 38. Thus, the fitting 32 is secured to coupler 24 of mask 12, whereas the opposite fitting 34 is threaded onto the box­mounted gas fitting (not shown).

[0016] In more detail, the tube 30 may be formed of an elastomeric material, and particularly those selected from the group consisting of silicone rubber materials. The sheath on the other hand is preferably formed of "Nomex" flexible fabric; the sheath could also be formed of other suitable materials such as Kevlar, Nylon, or monofilament. The sheath 36 has a length which is two to three times the length of the inner tube 30. As best seen in FIG. 2, in the relaxed condition of the assembly 14, the sheath 36 is in a gathered or shirred condition along the length of the unexpanded tube. However, as depicted in FIG. 3, when a pressurized gas such as oxygen is delivered into the tube 30, it expands in both radial and axial directions. However, the presence of the sheath 36 serves to inhibit and restrict the extent of radial expansion of the tube 30, but permits axial elongation thereof. Preferably, the deployed length of the hose assembly 14 is at least about 1.5 times the relaxed length thereof, and more preferably at least about two times the relaxed length.”

The judge rejected the allegation that McDonald deprives claim 1 of novelty for three reasons. First, he held that, considered as a whole, the assembly described and depicted in McDonald is not a garden water hose. With the mask attached, it is an aircraft oxygen hose. An assembly with the mask is not suitable for use as a garden hose. Second and on the assumption that the hose is considered without the mask, it has no flow restrictor. The judge was not satisfied that this assembly, in and of itself, would expand if connected to a water supply because there was nothing to restrict the flow of water. Third, the judge was not satisfied that the component (34) on the free end of the hose would fit into any domestic garden water supply.

That brought the judge to the critical question, namely whether it would have been obvious to an ordinary skilled garden water hose designer to adapt the hose described in McDonald so as to make a garden water hose. It was Tristar’s case that such a designer would immediately recognise that the hose structure could be used for and would work as a garden water hose. Blue Gentian responded that the designer would reject McDonald as having no relevance to the problem at hand.

The judge was not persuaded that the invention was obvious. He reasoned as follows:

“98.

Although a garden water hose designer would understand at a conceptual level how the hose in McDonald is supposed to expand in length as a result of gas pressure, I accept Mr Sinclair’s evidence that it would not be immediately apparent to a garden water hose designer that the hose would be suitable for use as a garden hose. He said that a garden water hose designer would see McDonald as being small bore, gas-actuated and without a valve. I agree. The garden water hose designer does not know how the mask and regulator works and they do not know what the gas pressure or flow rate would be. Although that information would be readily available to a manufacturer of aircraft equipment, it is not part of the common general knowledge of a garden water hose designer. I have accepted that a hose made according to McDonald by an aircraft equipment manufacturer would in fact expand under domestic water pressure but I am not satisfied this would be obvious to a garden water hose designer reading the document.

99.

Tristar submitted that the skilled person would recognise the principle of hose construction exhibited in McDonald and see that it could be adapted with choice of appropriate ready to hand materials, to the field of garden hoses. However in cross-examination Mr Sinclair was doubtful that a practical hose designer would use McDonald as the basis for a new product. I think that is right. Details will be important to a product designer.

100.

I think a garden water hose designer presented with McDonald and reading it with interest would be interested in the space saving quality of the idea but the designer would also see a document which was not addressed to him or her. The teaching is concerned with something used in an environment and context a very long way from garden water hoses and subject to considerations which the garden water hose designer would know they knew little about. For all they would know the idea is only realistic because of specific details relating to aircraft oxygen supplies and oxygen masks. They would not be confident the idea would be practical if applied to a garden water hose. Although it is undoubtedly the case that a person skilled in the art could arrive at a product within claim 1 if presented with McDonald, given that the hoses function in the same way, I am not satisfied the unimaginative skilled person working without hindsight would do that. I find that claim 1 is not obvious over McDonald. The same therefore follows for claim 14.”

Mr Wyand now submits that the judge fell into error in no fewer than five different respects. First, focusing on paragraph [99], Mr Wyand contends that the judge fell into error in attaching the weight that he did to Mr Sinclair’s evidence that he was doubtful that a practical hose designer would use McDonald as the basis for a new product. In particular, continues Mr Wyand, Mr Sinclair clearly had in mind the design of a commercial product and that this was setting the bar too high. Tristar only had to show that it was obvious to make any garden hose falling within the scope of the claim, whether commercial or not. Accordingly, so Mr Wyand submits, the judge was wrong to take any account of what Mr Sinclair said because it was legally irrelevant.

I have revisited all those passages of Mr Sinclair’s cross-examination upon which Mr Wyand particularly relies. Having done so, I have no hesitation in rejecting Mr Wyand’s submissions. It seems to me to be clear that Mr Sinclair was invited to and did consider McDonald from the perspective of an ordinary garden hose designer and whether it would have been of any interest to such a person in trying to design an improved garden hose. It is entirely true to say that in his evidence he talked about the importance of detail. But here I understand him to be referring to the detail of the new design, not the detail of a new commercial product.

Mr Wyand turns next to paragraph [98] of the judgment. Here the judge accepted Mr Sinclair’s evidence that it would not have been immediately apparent to a garden water hose designer that the hose in McDonald would be suitable for use as a garden hose, and that it would not have been obvious to such a designer that a hose made according to McDonald by an aircraft equipment manufacturer would in fact expand under domestic water pressure. The evidence of Mr Sinclair upon which the judge relied was, says Mr Wyand, manifestly wrong and Mr Sinclair failed to provide any plausible reason in support of the distinction he sought to draw between gas and water.

I recognise and accept that the judge found that the hose and mask assembly which a manufacturer of aircraft equipment would make on reading McDonald would expand in the manner required by the patent if connected to an ordinary domestic water supply and that the hose would retract again if disconnected. Nevertheless, the judge was in my view entitled to find as he did that this would not have been apparent to a skilled but unimaginative garden water hose designer. The judge was entitled to find on the basis of Mr Sinclair’s evidence that such a designer would not have known how the mask and regulator worked and would not have known what the gas pressure or flow rate in an aircraft would be. Unless such a person had a reasonable expectation that a system of the kind described in McDonald could be used as a garden hose there would have been no reason to take it forward. I am therefore satisfied that the judge was entitled to make the finding that he did.

Mr Wyand’s third point is very much like his second. He contends that in paragraphs [98] and [100] of his judgment, the judge concluded that the skilled but unimaginative garden hose designer would not have believed that the hose of McDonald would work as a garden water hose. Mr Wyand submits that no reasonable judge could have reached this conclusion. It is, he said, clear from paragraph [0016] of McDonald that the hose construction is of perfectly general application. All the designer has to do is to pick the appropriate materials depending upon the nature and pressure of the fluid to be carried by the hose. The designer would know there is no material difference between gas and liquid because they are both fluids and so McDonald would lead the garden hose designer directly to the claimed invention.

I accept that there are certainly passages in McDonald, for example in paragraph [0016], which appear to refer to pressurised gases other than oxygen. But there can be no doubting that the main thrust of McDonald is the provision of a system for ensuring the supply of oxygen to the crew of an aeroplane in an emergency and that this would have been immediately apparent to any reader. Having read Mr Sinclair’s evidence, I am satisfied that the judge was entitled to find as he did that the skilled but unimaginative garden water hose designer presented with McDonald would have considered that this was a document which was not addressed to him or her. It is, as the judge said, concerned with a system for use in an environment and a context a long way from garden water hoses. That is a field about which the average garden water hose designer is likely to know little or nothing, and the judge had an ample evidential basis for expressing the views that he did.

Mr Wyand next contends that the judge fell into error in accepting Mr Sinclair’s evidence that the garden water hose designer would have thought that the hose in McDonald has a small bore. Mr Wyand submits Mr Sinclair was not able to make any assertion about the diameter of the bore of the hose in McDonald and accepted as much during the course of his cross-examination.

I do not think there is anything in this point. Of course Mr Sinclair did not know the typical diameter of the bore of a hose for supplying oxygen in the cabin of an aircraft. But that does not mean to say that he could not express a view as to the impression that McDonald would have made upon the mind of the average garden hose designer. The judge was entitled to conclude on the basis of all of the evidence which he heard that such a designer would have considered that the hose in McDonald has a relatively small bore.

Mr Wyand’s fifth and final complaint is focused upon an aspect of the judge’s reasoning that appears a little earlier in his judgment. He said at paragraph [95]:

“Tristar submitted that Mr Sinclair accepted that McDonald would be of interest to the garden water hose designer if he was presented with it. However that is not how I understood his evidence (at Day 2 p155 ln5 to 156 ln25). Mr Sinclair’s view was that the garden water hose designer would be interested if they thought McDonald did explain how a hose could replace itself back in the box but he thought the skilled person would not understand how it did that. I agree. Just as a manufacturer of aircraft equipment would be concerned that the proposal had not been thought through and might not be practical as I have held above, so a garden water hose designer would have the same concern.”

It is, I think, clear from Mr Sinclair’s evidence that he was puzzled about the mechanisms involved in the expansion of the hose and at what point they were triggered, and that he was also concerned about the retraction of the hose and how it could be stowed. However, says Mr Wyand, there was no rational basis for accepting Mr Sinclair’s views that the issues with the box would be of any concern to the garden hose designer. First, he continues, the box described is plainly specific to the aircraft context and second, garden hoses do not come in boxes.

I recognise the force of Mr Wyand’s submissions but they seem to me to be directed to a point which the judge has not himself made. He concluded, based upon Mr Sinclair’s evidence, that the skilled but unimaginative garden water hose designer looking at McDonald would have been concerned that the proposal had not been thought through properly. I am satisfied that this was a conclusion to which he was entitled to come. Indeed, earlier in his judgment, at paragraph [79], the judge also recorded Mr Sinclair’s opinion that it was very difficult to understand how McDonald could work in practice because the hose would get tangled up if it expanded whilst still inside the box. Overall, the judge concluded that the skilled reader would think that deployment and retraction might work but that it was not explained clearly; it would at least require some careful thought and might well not be practical.

I would therefore reject Tristar’s challenge to the judge’s finding that the patent was not obvious in light of McDonald.

I am satisfied that the judge has carried out a thorough evaluation of the evidence before him and he has made careful findings. He has made no error of principle. In my judgment there is no basis for this court to interfere with the conclusions to which he has come. I would dismiss this appeal.

I agree.

I also agree.