What common calibres are in the UK?

[CharlesHarris]

MB has hit the nail squarely on the head! I have little to add.

Here in West Virginia and adjacent counties in western Maryland or south-central Pennsylvania the firearms you most likely run into at estate, barn and yard sales are .30-'06 or .30-30 "deer rifles", .22 rimfire rifles of all descriptions, 12-bore shotguns of all descriptions and either .38 Special or .45 ACP pistols or revolvers which Dad or Grandfather carried as a cop or in the Army.

You run into regional preferences for .32 revolvers, .270 rifles and 16-, .410 or 20-bore shotguns but the "Evil Black Rifles" and 9mm Parabellum or .40 S&W "Modern Cop Guns" are seldom seen outside a gun shop and are seldom purchased except by except those whose minds are corrupted by reading too many newstand gun magazines written by bar room commandos...

I would agree that the gentleman farmer armed with a .22 rifle, a 12-bore shotgun and either a .30-30, .303 or .30-'06 rifle and any serviceable pistol or revolver of .22 LR or larger calibre is adequately equipped. We must not over-think this sort of thing...