@Rhos Helyg LM - with respect, and by your own admission, you do not attend shows/displays where the public has close access to live steam models, at least, with your own models. My home ride-on 7 1/4" gauge society is insured by Walker-Midgely, as I am under a separate cover that looks after me if and when my own electrically-driven locomotive is operated elsewhere. Walker-Midgley require test certificates for any and all pressure vessels operated under their policies, regardless of size/capacity I'm also in the 16mm Association and the G1MRA and G Scale Society - all of whom has insurance cover by virtue of membership, but no little piece of paper that actually documents and certifies the safety of my boiler or gas tank apart from my own self-testing certificates. Now it seems that they are worthless, since they only certify that the safety valve operates at the correct release pressure, and that the pressure gauge operates, not that the boiler safely withstands twice the working pressure, or whatever it is the the gas tank is required to withstand safely. Hence the necessity for an 'uninterested' and independent boiler tester.
It can be construed that while I am operating my models at an open day, I am performing unpaid 'work' as a public service in doing so, and therefore subject to the H&SA, the same as the old guy cranking the little childrens' carousel.
My home society is now grappling with the interpretation of the terms of the insurance cover with regard to our little steam locomotives, of which there are a good number.
I am awash with trying to comprehend/interpret the new documentation.
Maybe this is all a storm in a teacup. However, reading the two documents - boiler and gas tank testing - tells me otherwise.
I note, with great interest, that nobody from any of the societies or manufacturers has yet chimed in with THEIR take on all this.
I guess that we'll have to wait.
tac