I do remember being in the T1 security queues once, and being asked to carry a "queue monitoring card" through, with the time marked on it, so that BAA could see how long the queues were taking. The time on it was correct.

Thing was, I was at the front of the queue, having been there for about 15 minutes, about to put my bag on the conveyor. I only then realised what was going on, so left the card on the side.

I wouldn't like to suggest that the two events are at all related.