Kwmpa, I don't have access to my approximate (very!) dating matrix right now but I'll have a look soon and tell you if I can offer any dating help. My guess is that it's about 1910 but I may be way out.
The 67** number range is often bad news as the owner at one time, a Frederick Woods, antique dealer and shooting enthusiast, imported a lot of Spanish barrelled actions (mainly sidelocks) in the white and had them finished (not particularly well) in the UK.
However, this looks like a standard wildfowling Birmingham boxlock albeit with nice, appropriate engraving. You didn't show the top lever but I would expect the simplified screw grip if not the full blown version.
If the latter, it most likely originated at Webley & Scott, if the former, it could have come out of any of the dozens of Birmingham gunmaker to the trade.