There's only ~40 on terminal stands at the North Terminal, some of which don't have an airbridge for the right hand stand.
http://www.ead.eurocontrol.int/pamsl..._2_EGKK_2-2_en
The BA based short haul fleet at LGW consists of
- 11 ex BMI A319s G-DBCA-K
- 1 ex BMED A320 G-MEDK
- 9 second hand A320s with the tenth having fallen through due to QA issues, the 10th is currently at Woensdrecht
.
For the summer peak a number of LHR based A319s are rotated through as required but BA are still not even half the size of easyJet in short haul.