Originally Posted by corporate-wage-slave

Unlike T5 it is relatively easy to leave T3 from airside. The easiest directions I can give you is go to the American Airlines lounge (Lounge H on the unhelpful Heathrow signage) then move towards the former Flight Connection corridor area and you will then see the signs saying "Flight Connections" in purple, and yellow signs for "Arrivals". The latter is the one you want, but if you don't see Arrivals then follow Flight Connections sign until you do.

Welcome to Flyertalk and welcome to the BA forum PeeterL, I do hope that we will see more of you here.