British guns & rifles are kind of my "thing" so I have a few interesting ones:
Rigby Rising Bite 12 bore hammer SxS shotgun 1882
Alexander Henry & Co. SxS shotgun ~1903

GE Lewis 8 bore double rifle ~1879-80
H&H Paradox 10 bore double gun 1898
Joseph Lang & Son 12 bore double rifle 1868
WJ Jeffery .577 BPE hammer double rifle 1896
W&C Scott .500/.450 3 1/4 NE hammer double rifle 1899
Rigby 10 bore muzzle loader double rifle 1854
Rigby .577 2 3/4" BPE hammer double rifle July 1894
Rigby .470 NE hammer double rifle 1919
Rigby .450 3 1/4 NE hammer double rifle 1903
Rigby .450 3 1/4 BPE hammer double rifle 1872
Rigby .500/.450 #1 Eley BPE double rifle 1893
Rigby Mauser 98 .275 HV Aug 1936
Charles Boswell Lee Speed .375 EX (2 1/2" Flanged) 1909
Vickers Ltd. .242 Vickers Express double rifle ~1923-1927
Cogswell & Harrison Mauser 98 .242 Vickers Express on/after 1933. (4 digit Vickers Serial number)
Cogswell & Harrison "Tranter Double Patent" single shot .500/.450 #1 Express ~1870 (externally looks like a Martini)
Cogswell & Harrison CERTUS .450/.400 3 1/4" March 1903

Webley Mk IV .455 (Boer War Era)

A few other BP Express rifles, but the above are the "interesting" ones.

- Mike