If anyone knows Biggin particularly well, I was doing circuits on 21, only to be asked to follow someone who was downwind. It turned out he had 'extended' crosswind and was actually flying downwind almost over Croydon......
I'm learning at Biggin. I've been taught 2D's "over the shoulder" technique for flying the circuit which seems to work fairly well, and there are a few useful ground features such as the gypsy camp and the round building near the hospital to provide a reference. Can't say I have seen anyone disappearing off to Croydon when I've been circuiting, but there have been a few occasions where I have been asked to orbit downwind in order to slot in behind someone doing an ILS approach.