Snapshot
Thanks for the info, but I think you will find that these guns will be listed as "Humane Killers" or some such definition. it's all down to wording. As I said before you can get a "short barreled rifle" which is a long barreled pistol style gun with rearward extensions (usualy in the form of a counterballance for the extended barrel) which takes it over the minimum overall length for a handgun. So what you get is a long barrel pistol weighted and balanced to compensate for the barrel.
On a different tack you can actualy legaly buy and use an 1851 Colt Navy Carbine (Buntline Special to wild west fans) since it is a black powder revolver and these are deemed licencable (probably because of the restrictions imposed by use of black powder and the time it takes to reload). Replicas of these will cost around £150:00 from Henry Krank. http://www.henrykrank.com With a very deep pocket you could possibly get an orignal. You still need a FAC and additional storage for the black powder.