Got my BGA log book here, so here are the ATC gliders I've flown- either in ATC use, or in civvy hands-
WB991 -T21
WB922- T21- first solo!
WB963- T21
WB942- T21
XN148- T21
WB958- T21
WJ306- T21
WB962- T21
WG498- T21
R92(Milreg?)- T21
XA310- Mk3
XN253- MK3
XN240- MK3(currently in Belgium)
WT877- Mk3
XA308- Mk3
XE791- Mk3
WT919-MK3
WT903-Mk3
WT908-Mk3
Swallow- XS651 (Currently in Cyprus)
plus now of course, Prefect WE992