I would guess (guess) that the number of serious (however defined) collectors with large (say twenty plus?) collections is something like 500. Maybe 2000. I base that on things like active and passive membership of relevant web forums, FB groups, etc.

Binners might have a view - attendance at Kempton fair, divide by two given it also had militaria and stuff, then multiply by some factor as I guess few people more than three hours drive from London (which I guess is something between a quarter and a third of the U.K. population?) would have made the trip.

There are of course a much larger number of airgunners who own an old rifle or pistol from their youth, or inherited from a relative, or that they bought because it was interesting, but would never visit this section of the BBS, or consider themselves "collectors".

I'm not even sure if I'm a real collector. I do own a fair few airguns, almost all of them are old, many are definitely collectable, but I think I have accumulated them because they are interesting, not because I wanted to collect things.

Oh, alright, I guess that means I'm a collector.