Off topic a bit as my experience did not happen in a "Games Family" lane:
Riding round Parliament Sq turning into Birdcage Walk, I very nearly got cut up on the left hand bend by an undecorated 7 series BMW, but I took the bend wide, forcing the car wider, to give me room to manouvre. I then found a lot of slow cyclists riding on the left, so I maintained primary behind a Games BMW (and kept up with it) to pass the slower cyclists. As soon as I was passed them and before I had any time to move over, the 7 series behind flashed blue lights and sounded a siren. OK, unmarked copper, move over then. Err no, as the car pulled alongside me, the passenger in the front seat said something that I could not make out in what I think was Spanish - he was definitely not a British police officer, so I "welcomed" him to London in the local vernacular.
I guess it must have been some diplomatic protection officer from the visiting country. I shall be showing less respect than usual for blue lights on unmarked BMWs in future (although maybe only when in the car). ...unless of course the Family leave a horse's head in my bed tomorrow morning!