Under the "G", looks to me like a Fleur de Lys?
The design of that Crown on the front site looks like some German style crown proofs (more rounded than the usual British ones), but I'm only speculating. The "G" also kind of makes me think German. The overall trigger guard styling to me looks Germanic as well. But.. again... only guessing - get the conversation started anyway.
I would have to agree with your views. The lock has no markings visible on the outside. Haven't pulled it you.
The barrel also has a double strike that is matched by the same on the underside of the forend proving they were made for each other.![]()



























