That is a high end gun. It has english barrels by Joseph Whitworth. It is one of a matched pair. A 12 gauge that was nitro proofed. It was proofed between 1910 and 1924. At the time of proof, the barrels weighed 1.6616 Kg or 3.55 lbs. It was made for 2 3/4" ammunition.

http://damascus-barrels.com/Belgian_All_Proofmarks.html

There is punch on the barrels that says "trade mark". I can not make out what that mark is. Also, as Geno asked, is there any markings on the top rib or any where else on the gun?

Pete

http://www.damascus-barrels.com/Movie.html