That is quite a tale, well done for persevering, a lesser mortal may well have given up! Accepted there is often different sides to every story but from your account, for me anyway, it raises a few questions.
The request for the club to test it; fair enough I can understand reluctance to test it with cladding on and mounted to the frames without any previous history. However, any reasonably competent club tester could have said “if you dismount it and pull its trousers down we can give it an inspection and test it as a new boiler” (2wp). This is the sensible approach and it sounds as if that is what Western Steam did. For a copper boiler there is nothing in the club code that prevents this approach either that I am aware of. If a club tester feels he could not make a judgement on this (as his right under the code) then I would perhaps be nervous about asking him to do a retest on an older copper boiler. Just because it doesn’t leak at 1.5wp cold doesn’t mean it doesn’t have a defect like an internal failure of a silver soldered crown stay that has caused deformation of the crown – the visual is just as important as the pressure test!
TSW I am assuming were given the brief just to pressure test it without performing other work? If it leaked then fair enough it failed the pressure test. However the leap to the conclusion the boiler is toast without investigating or recommending to you they do further investigation to confirm where the leak actually was is possibly a bit of a stretch, maybe they did say they needed to dismantle further to investigate?
WS took absolutely the right approach I would say. They asked for the bare boiler, pumped it up, gave it a good looking at and discovered the leak was nothing more than a fitting. In truth they did no more than your club could have done and if they were not comfortable in doing that then Les’s comment bears some serious thinking about and maybe you should ask before putting it back together if they will be now be happy to do the 1.5 on the frames and the steam test? I can only suppose that if they are, their comfort will be from someone else underpinning their work?
To me this just illustrates how subjective a boiler test can be dependent on the inspectors experience and perception of risk and the brief they are given. You could well have ended up scrapping a perfectly serviceable boiler!
For screwed fittings and gaskets if you must apply sealant to gaskets Rocol Steamseal is your friend.
Paul.