Hi Matt
As Jon has said it was on the stand behind ours, the trader told me it came from a house clearance of a deceased engineer, it had no markings so no clue as to whether it was made for personal use or a company prototype
The trigger guard formed part of the cocking Lever which was hinged at the muzzle, you loaded it by u nscrewing a plug at the rear of the cylinder
It did attract a lot of attention
Bob