A security car following the Prime Minister’s vehicle went behind Johnson’s car and left a visible pit.
The story emerged after a crash video circulating on social media.
Johnson’s official spokesperson confirmed that the video showed the Prime Minister’s car and was inside at the time, but said it was harmless on the shunt.
“Yes, it was the Prime Minister’s car,” said the spokesman. “I think the video speaks for itself about what it is. There are no reports of anyone injured.”
“The pedestrians are reported to have stepped on the road and caused the vehicles to stop suddenly, causing two of the vehicles in the convoy to only get involved in a damaged collision,” London Metropolitan Police said.
“The man was arrested for crimes under section 5 of the Public Order Act and the motorway obstruction”, and added that all relevant vehicles were “driving from the scene”.
Downing Street said it would not comment any further on the subject.