Originally Posted by
heckenhocker
You will go through customs at BSL. At LHR you will stay airside (unless you take a wrong exit!). If you find yourself in a queue to show your passport, you are in the wrong place...find someone in a uniform to give you directions.
If you are in a queue to show your boarding card, you're in the right place

If you have one ticket for the whole trip (PHX-LHR-BSL), then BA will sort you out if the flight from US is late arriving and you miss the BSL flight.
Yes, BA has moving map and movies. No charge for these. Headset is provided, but you may find your own headset is better quality / more comfortable.
Enjoy

Thanks for your efforts. I appreciate your helps. I will lookout for next connecting flight, but is the flight always on-time performance? I wasn't sure there is lots of aircraft are awaited for landing. Due to the congestion. So I should be okay. I don't have worry about my next flight to BSL.