Terminal 5, as I said — nowadays all BA flights go there, so there are flights from all over the world there (the distinction between the other terminals is bas

Terminal 5, as I said — nowadays all BA flights go there, so there are flights from all over the world there (the distinction between the other terminals is basically that of airline, the fact a lot of Asian airlines happen to be in T4 is coincidence rather than explicit planning, AFAIK). I am British — which helps somewhat — but I've known them to throw us on the back of the "All Passports" queue when it's been relatively busy, and never noticed it take any longer than otherwise. That all said, I more often than not pass through the passport control used for domestic transfers, rather than that for leaving the airport (though my experience is that that tends to have shorter queues than the one for transfers). And no, I wouldn't expect being from the US to help, except for not requiring a visa.