Ah, thanks Enfield Trader. I was not aware that a stamped backsight was made for the No.5. I have had experience with the stamped Mk.3/4 backsights on the No.4 and have not much good to say of them other than their being sometimes authentic - too fragile and the battle peep being too easily 'butt-stroked' off by another rifle placed less than meticulously alongside. Still, interesting and an education for me. I should likely be embarrassed for not knowing about the 'Mk.2 backsight' for the No.5 but I'm relatively new to the LE. ed