My wife and I flew from NCL to BUD with BA via LHR a few months ago. As my wife has mobility problems we required wheel chair assistance at LHR T5, this was booked through BA. A member of the cabin crew when we arrived at the gate in T5 knew exactly which seat my wife was in came and told her to wait until all the other passengers had disembark and that a wheelchair was waiting for her. We were escorted to a waiting area in T5, and when the gate was know for our onward flight escorted to the aircraft. The same on the return journey, this was a free service done with care and courtesy.