Originally Posted by
NWIFlyer
If you're on a BA metal flight then by default your bags will be through checked and held in LHR overnight. You would have to specifically ask for a short check, which is only routinely granted for overnight connections when it's recognised passengers may need clothes etc from their bags. You need have no concerns about this particular aspect - it's just about the most certain thing in your whole plan!
If you have no baggage to claim, you also have the option of transferring airside using the Flight Connections buses, and then clearing immigration at T4.
we were told that years ago when flying on LX,SN and LH and every time since our layover was 10+ hrs they refused to check them all the way thru, although apx 6-7 yrs ago they did check them thru but no longer. The BA rep of the phone said it depends how they handle it at your Departure Airport since its Rent A Crew who knows what will be