A part of the Tory Government 1988 Firearms Act that prohibited self-loading and pump action centrefire rifles also moved multi-shot self-loading and pump action shotguns to s1 if they had a magazine capacity of more than two shots or a detachable magazine. At the time I had a 16 bore Browning A-5 that would be affected by this.
It was duly added to my s1 Firearm Certificate (possessed to shoot "flocking birds") and I was asked to produce evidence of the land that it would be being used over. This was in the old days of a land condition requiring a named piece of land. So "For use at X" or "For use and X and any other land deemed suitable by the Chief Officer of Police for that area" or "For use at X and any other land".
My stalking rifles were the last most "For use at X and any other land". What I remember as the old "Condition III" as a fully open FAC was known as. So they asked what land I wished to nominate as being for this 16 bore A-5. So I told them the cottage its pond and surrounding farmland that at that time I owned known as "Pooltail". To which I was told they'd have to inspect it.
I pointed out that I shot duck on the land, plus at that time avian vermin...flocking birds, and that I could also do this with a side by side 12 bore, 10 bore, 8 bore or whatever and that therefore why did it now need to be inspected and approved for a mere 16 bore albeit one that as it had a four shot magazine was now classed as s1.
The point was taken. The condition was added "For use at Pooltail and any other land" and an inspection and approval was not deemed necessary. But looking back it may well be that if all shotguns on s2 were moved to s1 that owners would have to produce evidence of "good reason" which if not membership of a clay shooting ground and regular attendance there would perhaps require proof of which land the things were to be used over and proof or regular use over the nominated land.
Recall that after the Tory Government Dunblane legislation the rule of "use it or lose" it was made law in relation to s1 weapons and that proof of use can be required. No proof of use resulting in no longer any "good reason" and possible revocation of the authority to possess that particular weapon. To which see below regarding "grandfathering":
The "grandfathering" of shotguns kept for sentimental reasons but no longer used is permitted under s2. If be effectively ceasing to be allowed (by the fact all now coming under s1 remit which doesn't allow such) that old side by side kept only as a memory of a long passed family member or friend "This was once your grandfather's, Great Uncle Ned's, Captain Smith's at the Top Farm (or whatever)" may no longer be able to be retained.