Robert Largan, another MP, said: “Words matter. What we say and how we say it echoes out far beyond Parliament. It can have serious real-world consequences. Elected representatives have a responsibility to lower the temperature of debate, not add fuel to the fire.”

Sir Roger Gale said: “This, I fear, is the direct result of the deliberately careless use of language in the Chamber.”

Dame Eleanor Laing, the deputy Speaker of the Commons, said: “This is unacceptable. Period. Elected representatives must be able to go about their work without the fear of verbal or physical attacks.”

One video on social media showed Sir Keir, surrounded by police, being followed down the street while being targeted with shouts of “Why aren’t you opposing?” and “Traitor!”

“Why did you go after Julian Assange, why did you go after journalists?” one man shouted.

It is understood Sir Keir was not harmed. After he was taken to safety, an officer was called a “pathetic little thug” during angry exchanges.

On Monday night, Mr Johnson condemned the scenes but failed to apologise, tweeting: “The behaviour directed at the Leader of the Opposition tonight is absolutely disgraceful. All forms of harassment of our elected representatives are completely unacceptable. I thank the police for responding swiftly.”

Protesters were seen displaying signs opposing mandatory vaccination and the use of restrictions to prevent Covid deaths, and were later addressed by Piers Corbyn, the Covid conspiracy theorist brother of Sir Keir’s predecessor, Jeremy Corbyn, who led chants of: “Resist, defy, do not comply!”

The incident came after Sir Keir said that it was “up to the Prime Minister” whether he apologises for his Savile comments.

He said that the culture in Number 10 would only change when “the person at the top changes” and reiterated his call for Mr Johnson to stand down.

“I’m concerned about standards in politics and acting with integrity,” he said. “So this is not about me – it’s about how we conduct ourselves. It’s up to the Prime Minister how he conducts himself. But I don’t want to see the lowering of standards, the slurring of anyone in politics. It’s not about me. It’s about the sort of politics that I stand for.”

A Labour source said: “Keir was back at his desk straight after, and he’s still going to his five-a-side game tonight. Nothing gets between Keir and his football.”