snookered?

There's an old urban myth about policemen booking cars for speeding in a particular sequence like in snooker. A red car between every other coloured car and then in a particular sequence finishing with black.

So yesterday when I was in central London I smiled when I saw four unmarked police cars in different colours blue lights a'flashing speeding in procession through the traffic near to the City of London. They were all in different colours, but I don't think there were any reds.