The ex-BMIbaby were never going to be brought into the BA fleet. Currently in storage to be scrapped/sold.
As for the Gatwick 734's, they are soon to be retired. This will be a slow process with the first one due to leave the fleet around May this year.
Have it on good authority that from the start of the summer a number of ex-BMI A319's (6 I believe) will be based at Gatwick.
Ex-BMI A320 G-MEDH currently being returned at the end of its lease.
Lease due up on one BA A319 shortly and looks likely to be returned.