Les,
Thanks a lot for posting this close-up. The turret number '21' is consistent with 'A' Squadron, and would make this tank part of 2 Troop 'A' Sqn 1 Lothians.
Other markings are not readable but could include the AoS number '52', the tank name and T-number, plus maybe some loading code:
The name of the tank should be one of these four, since No.20 was RHODERICK DHU T212645, see
http://proxy.handle.net/10648/ac053d...8-003048976d84
ROB ROY
RED DOUGLAS
RED COMYN
RED TOD
Maybe the name could be guessed if the original photo is a good print and could be further enlarged ?