I have a similar W&C Scot&Sons with identical engraving but without the half moon stock. The sn is 616xx and I have been told that it is circa 1899. The heads of the pins through the side of the action are convex unlike yours. It is an ejector with crossbolt action. The pat number is s 259-93 Use number 1918. Barrels say W & C Scott and sons makers and London England. Also on Flats Nitro Proof 1 1/4 oz shot? Was it nitro proofed later?
Regards
Dblfixer