What a lovely gun!
It appears to be in quite good condition, too.
We've learned from Rocketman that a fair market value for British breech loading sporting guns of the late 19th to mid 20th centuries can be a function of brand, grade and condition.
There appears to be no similar table of information for the earlier muzzle-loading era though; you do have a top name, in a high grade and good condition; Cased? Provenance? Single, or originally one of a pair? Worth at least a few thousand, I'd have thought, perhaps 1/3 to 1/2 of a breech loader, all other things (ie name, condition, grade) being equal...
RG
