"I do not feel that Holts is about to be flooded with masses of old British shotguns going for a song and ripe for export to North America, though!"
If they can not be shot why would they not head to the only market for them? If they hold no value to shoot what are they then? An asset to sell, to get some value out of, or a relic to keep with little real interest in ever using. I have dealt with these issues with antiques and fine china from family estates. Nobody wants them, only some of the value. Your fellow shooters are facing aging out of shooting and now having their guns made almost impossible to shoot, at the same time. Once they pass their guns will need to be passed on to heirs with no interest in them, made worse because they can not even use them at all. I know they are working on lower pressure steel shot loads in 2 1/2" but they are only of interest to those willing to shoot. Few young people are, fewer with a double. Falling generational interest as you pointed out has already decreased demand. Making it harder will decrease it further. Supply and demand with decreasing demand gaining every day.
