In Britishicon and Commonwealth service, barring out with a file or using a cancellation stamp was the norm when telescopes were swapped out or upgraded. That way, the history of the weapon was somewhat "readable". If you find one filed off and renumbered, be cautious. Later, in the L42A1 era, I've seen where an Armourer cut out and patched the wood before renumbering it but it was later in the game and many of the old timers were retired and a new crop of youngsters were running the show. I've also seen rifle serial numbers stamped where the telescope number should be on the L42A1. I guess the best explanation is that it was the end of an era.

I have a 1943 No.4T with four scope numbers on the wrist. You can read all four numbers, (some barred out with a file and the others stamped with the real cancellation stamp but still readable), and I actually found the first matching scope in a bucket of derelicts in DRP's garage with the help of Peter Laidlericon many years ago who found it listed in his data base so have the first and last matching scopes for that single rifle. Thanks to both Roger and Peter for their attention on that one!