I am afraid that this is going to be a very difficult one to identify, unless there are some markings on it which do not show in any of your photographs. This appears to be a double-action only revolver, with several strange aspects to it. Generally, it appears relatively crudely made, with poor finish work. This, and the upward-opening loading gate (which is relatively unusual), makes me wonder if it was not a mass-production revolver, but was one built by hand in a small workshop. The fact that the cylinder must be removed to reload would certainly make it far from optimum as a military arm. The checkering on the grips does not look military. I have reviewed all my handgun textbooks, and have not been able to find anything which looks even remotely similar. It certainly is not representative of any European nation's standard arms. I cannot figure out the purpose of the long straight piece on the frame on the right side-- is it some kind of a spring? The bottom line is that this appears to be a non-military weapon, probably of the late 19th century or early 20th century-- I would guess probably 19th century rather than 20th. At that period, small workshops specializing in the production of crude armaments were common in Belgium, the Eibar Region of Spain, and further afield in Afghanistan and Pakistan. It could have been produced almost anywhere. If there are any markings on it, (e.g. inside the grips, under the barrel, or on any of the small pieces), I'd be happy to try to see if I can identify it, but it does not look like anything produced in large quantities-- It could very well have been produced by a single workman with some basic tools. If you could get a chamber cast made and provide the measurements, figuring out the actual cartridge it was made to use might be possible. Unfortunately, your photos do not clearly show any dimensions (i.e. how big it is), or the diameter of the bore, etc., which would be needed to really identify it. It might be a nice keepsake, but I am not too familiar with British firearms laws, so I would recommend that having your local police tell you whether or not it is a prohibited weapon would be a very good idea. As I remember, if it can be used with any available ammunition, it is prohibited in the UK, even if the gun as a whole does not fire safely or consistently. Sorry to not have been of more assistance.