Does it matter? They are easily identifiable by the random berets, cap badges and stable belts stolen from other units, and their tendency to leave any car they come across on bricks.
PS I actually don't know what letters they use.
For the record...
I am from Leeds UOTC, but was born in the Midlands. I know that there are several other Leeds people who pop in from time to time but are obviously staying anonymous. I would start a thread for me, but it would only gets swamped by ULOTC types being confused and trying to expand their empire.