Thank you, Smokeless!

Section 58. . . that's what I was thinking of. It's similar to our (US) law about antique cartridge guns: but I have to admit that it makes more sense. Our law exempts cartridge guns made before 1899: regardless of caliber. So you have some guns in perfectly shootable condition, chambered for ammo calibers available at your local sporting goods store, that are exempt from gun control laws.

That's provided it was made in 1898, or earlier. Another specimen, same make, model and caliber but made in 1899 or later, WOULD be subject to the gun control laws.

What's the cut-off year for a muzzleloader being regarded as off-ticket in the UK?

Jim