I've seen some anecdotal evidence on here that a T3 --> T5 connection can still use the T3 lounges, although it is a bit more dificult than the streamlined going to T5. Will be at LHR around Christmas on a 5 hour layover, barring any schedule changes. Would we be able to come off our AA flight in T3, use the CX/QF/Centurion lounges (we will have access to all 3), then head over to T5 a bit closer to departure?