Thanks guys.The gun was originally chambered 2 , its not stamped on the barrel flats, but rather on top of the barrels, kind of unusual I guess. I think it is likely pre-1921 as there are no date mark stamps. I had originally thought that the Winchester AA Low Recoil loads were okay, as the Dealer/Gunsmith I bought the gun through said it would be okay to shoot low brass shells in it. Luckily no damage, the barrels still ring like a bell. Its a nice gun, my favourite because its English, and pushing nearly a 100 years in age. The gun was used very little judging from the condition. Was from an estate sale, the guy said his father had bought it in the 1950's, and only shot a couple of boxes through it then put it into the closet. It obviously had another gentle life before that. I have owned it since 1991. I will try and round up some Gambore English traditional loads.
Tim