I have not disassembled the gun.
There may be the remains of proof marks on the top-left part of the barrel, just forward of breech. But it is so badly rusted they cannot be made out.
Some previous owner carefully painted the iron parts black. So it doesn't look quite so rusted in these photos.
French would be my GUESS as well, unsupported by any evidence to date. Thhere is a photo of an English pistol, I. Lambe, with a lock like this one about 1730, Great British Gunmakers 1540-1740 but it seems to me unreasonable optimism to date my pistol that early.