Mr Khan was about to start speaking to the Fabian Society in London when he was disrupted by protesters from a group called the White Pendragons, who shouted pro-Trump and pro-Brexit slogans.

It came after a tweet by Mr Khan on Friday, in which he said Mr Trump had “got the message” that he was “not welcome” in London after the President cancelled a planned visit to open the new US embassy.

. . . . As security began to appear, those in the audience started to heckle and slow-handclap.

But a demonstrator, unperturbed by the reception, said: “We stand under common law jurisdiction.

“If you touch us, you’ll be done for common assault. Please stand back, do not touch us.

“We’re not leaving, we’ve paid for a ticket.”

The demonstrator also accused the Fabian Society of “subverting” the constitution.