Supercar drivers gathered on a bridge across the river Thames in west London as the region was thrown into a newly-created Tier-4 lockdown to try to contain a more transmissible Covid-19 mutation.
Police struggled to deal with the tailback of vehicles in at least three of the four lanes, with engines revving and traffic moving so slowly that drivers and passengers could get out of their vehicles to chat and film the meeting.
The supercars, some with modified engines, included BMWs, Mercedes and Audis.
In one video shared online, Chelsea Bridge, which spans the Thames in one London's most affluent areas, is jammed. For drivers crossing from the south, the route offers a short, straight run up to Knightsbridge, Hyde Park and Notting Hill.
The London 999 Twitter feed posted footage of the gathering, calling it a ''car meet" for boy racers.
One social media post said police should "confiscate the lot" but another said: "They aren't really blocking anyone. Traffic is just slow as people are parking for the car meet-up/burger stand. It's midnight on a Sunday night, I think what they are doing is fine."
The meeting took place on Sunday evening, the first day of the new Tier-4 lockdown created to suppress a mutation of coronavirus believed to be 70 per cent more infectious than the previous strain.
The list of restrictions for people living in London and most of England's south-east includes orders to stay at home unless there's a "reasonable excuse", such as work or education. People can meet one other person from another household in an open public space, but must be on their own to do so.