Protesters from the Unite union lay siege to Boris Johnson's car on Tuesday, as the mayor returned from a visit to a container port in Essex.
The demonstrators managed to stop his silver Land Rover by surrounding it and jumping on its bonnet - before the mayor eventually managed to make a speedy getaway.
"Give us a smile Boris," one protester can be heard to shout. "Boris, come on. Talk to us."
The protest mobbed the mayor as part of a campaign to get the owner of the port, DP World London Gateway, to recognise the union.
Jane Jeffrey, a regional officer for Unite who was at the protest, said it was important that Boris be made aware of their campaign.
"We're down here today because we've had a long struggle today with owners of the port to get union recognition," she said.
"We think it's vital in the industry that unions are in the workplace. This will be the only port in the country without a union. And when we head that Boris was here to support them, we decided to come along and let our presence be seen."