Actually, BA is retiring all but 9 of their 757s.
All in the G-BIK* range are to be rid of,
all in the G-BMR* range as well [both of these sets have the C engines, the less powerful, more fuel thirsty and older engines]
and then they are keeping either the G-BPE* fleet or G-CPE* fleet, probably a combination of both, some of the G-CPE fleet was only delievered in 1998 i believe.
G-CPEP is with Air2000 at this point, not sure if its a lease or it was sold to the airline.
They are all to be replaced with A320s and a couple of A321s, and the 9 757s left will be used on the Shuttle servie within the UK, and a few shorthaul Euro routes.
by the way, of the aircraft, they have/had 19 with the newer E engines, and the rest of the 53 were C type.
And currently there are only 18 757s left in the fleet [source:http://www.avnclub.demon.co.uk/fleetstats.htm