Case for Optical sight for British 6 Pounder Anti-Tank Gun. The case's lid is attached to the cylindrical case by a chain. This gun was used by British and Commonwealth Forces including the Seaforths in Sicily and Italy. The Six Pounder replaced the Boys Anti-Tank Rifle and the Two Pounder Gun in March1943. By this time, the Seaforths had a dedicated Anti-Tank Platoon in the new Support Company. [Roy, pages 118 and 136].