I arrived back at Heathrow today from Madrid on Iberia. The plane was scheduled to land at terminal 2 and the little yellow number at the gate did, indeed, start with 2.
However, we seemed to be in a bizarre Monument/Bank terminal-duality situation. As soon as I left the plane, there were loads of signs saying terminal one. I followed the most obvious route and ended up at a sign telling me to turn left for Terminal 2 passport control and right for terminal 1. Weird! I never knew there was a secret little passage between them.
I took a gamble and stuck with T2. It paid off as there were no queues at passport control. However, now that I know that you can move between T2 and T1 on arrival I'll have to devise some new "getting from the aircraft to the Heathrow Express in minimal time" strategies.... after all, T1 is closer to the heathrow express than T2. And every second counts :-p