The Jepp chart seems to correctly label the A3500 floor of the LTMA which runs in a narrow N-S band in the Henley-Reading vicinity.
I do not see a Jepp label for the A2500 floor on the boundary immediately East, but an A2500 label should be somewhere in the bounded area. Just how far away is a good question.
I would pencil in A2500 over by Twyford.