The instructions and parts list supplied with the long barrelled Shadow/Trooper, 'A' & 'D' series, are marked exactly that, but it certainly confuses the issue when the short barrelled Shadow, of which I've only seen a 'R' .22 example, is included in the mix.
It would appear the 'Trooper' was exported, whilst the long barreled 'Shadow' was sold in the UK.
I don't know how true it is, but I was told some time ago that a gun shop in Wales bought a quantity of Long barreled 'Shadows' from BSA, which is where most, if not all of the UK sales originated.