This is interesting.

Mechanically the gun bears almost all the marks of a similar Prussian Daly of the period (forend lug, action bolsters, shape of the dollshead, etc, etc.), to include the engraving pattern.

It is the marking ahead of the abrrel flats that are the head scratcher. The mark ahead of the serial number is a new one on me. I can't quite make out what is inside the circle under the crown (??). By chance are they crossed pistols that the vertical line is runing through? The serial number also does not fit in with any other period makers I could find, but that is less surprising.

Is there an Anson & Deeley brevete mark on the breech face?

Ken