Moosedog.If you need help in researching the gun in the British records, contact David Penn, through the Imperial War Museum in London. David is an honorary member of the S&WCA and now retired Curator of Exhibits at the Museum. I have a similar .455 T-Lock, ser. # 800 of the 5K British Contract 1st Model .455 HEs made. David informed me that my gun is the best marked British military T-Lock he had seen , as it met all the requirements of the regulations on correct marking of unit small arms, a duty of the unit armorer, which was often times overlooked during war time. The gun is stamped on the butt of the walnut grips with "53 S RFC 29" meaning " 53rd Squadron Royal Flying Corps, rack # 29" The 53rd Squadron flew Sopwith Camel fighter planes in the Mesopotamia campaign in support of the Bengal Lancers and Lawrence of Arabia's Arab Legion fighting the Turks. Many historic S&Ws wound up in the US after the British gun laws required their forfeiture to Police for destruction, or removal from Britain. The mark on the upper left side of the frame of your gun is the Crown Ownership mark applied at, I believe, the Enfield Lock proof house. The crossed flag stamp indicates the gun was "sold from stores," in some references but is a proof mark in most references. If the stocks are original and numbered to the gun, then they escaped the regulation required markings on their butt. Ed.