We often came across the other makes of Tele Sct Regt scopes and they were a problem. The spares were all, seemingly, from B&C and some wouldn't even remotely fit the telescope you were working on without a lot of bench fitting or lathe work and a thread file. That was the reason why many just got the chop. A lot of those from Ordnance went into the watch towers along the Irish border. Then the very nice Swifts came out. Nice to look at but equally troublesome until the maintenance group got to grips with them and authorised locking down the adjustment mechanisms, leaving only the focus adjustable.
You could have 5 sets of spare parts for a Sct Reg scope but still couldn't get it serviceable to the EMER spec. Even B&C spares wouldn't necessarily fit B&C scopes.
Someone mentioned RAF regiment snipers. The RAF kits had some really nice B&C telescopes in the kits. One type I remember was the little x20 BRITANNIC scope and another the x20 NELSON scope. Both the same but a different nautical name. I kept a Britannic when I had a chance to write one off and it is marked 'A crown M above 1940 above the RAF part number 9E/857' with the B&C logo too. Quite why the RAF needed sniper kits was something we often wondered about........