Sounds exactly like an episode of “Twenty-Twelve” on BBC America!
The explanation for the traffic jam the other day was that London’s road system is so *efficient* that one little mishap just wrecks the whole thing.
Huh?
I visited relatives in England many years ago. They picked me up at Gatwick and then proceeded north through London to get back to the Midlands. We got on the M25 and went around London in a circle 3 times. They said they don’t like to drive in London because it’s a mess. (No chit!)