Sir Keir was bundled into a police car for protection near Parliament on Monday as he faced baseless allegations of “protecting paedophiles” and protesters shouting about Savile.
At least six Conservatives including a former Cabinet minister joined MPs from across the political spectrum in linking the harassment to the baseless claim Mr Johnson made while under pressure over the partygate scandal.
Mr Johnson had falsely claimed Sir Keir “used his time prosecuting journalists and failing to prosecute Jimmy Savile” while Director of Public Prosecutions (DPP).
Coming under renewed criticism, Mr Johnson tweeted the “behaviour directed” at the Labour leader was “absolutely disgraceful” but did not address the nature of the abuse.
Julian Smith, who previously served as Mr Johnson’s Northern Ireland secretary, tweeted: “What happened to Keir Starmer tonight outside parliament is appalling.
“It is really important for our democracy & for his security that the false Savile slurs made against him are withdrawn in full.”
Former minister Stephen Hammond, one of the 15 Tory MPs to have publicly called for Mr Johnson to resign over alleged Covid breaches, said he agreed with Mr Smith, as did Robert Largan and Aaron Bell, who were elected in 2019.
Senior Tory Sir Roger Gale urged Mr Johnson to make a Commons apology on Tuesday over the abuse which he feared could be the result of Mr Johnson’s “deliberately careless” Savile allegation.
“It has, I’m afraid, played into the hands of some rather unpleasant people,” the MP, first elected in 1983, told the PA news agency.
“I think what he ought to do … is to go to the despatch box tomorrow to condemn the way Keir was treated and apologise.”
Tobias Ellwood, the Conservative MP who chairs the Commons Defence Committee, told the Prime Minister to “apologise please”.
“Let’s stop this drift towards a Trumpian style of politics from becoming the norm,” he added.
Officers stepped in to protect the opposition leader as the group, some protesting against Covid measures, followed him from outside Scotland Yard.
On at least two videos posted to social media, a man and a woman were heard shouting about Savile to the Labour leader, as he walked with shadow foreign secretary David Lammy.
Scotland Yard said two people were arrested on suspicion of assault after a traffic cone was thrown at a police officer during the unrest.
Mr Lammy said it was “no surprise the conspiracy theorist thugs who harassed” Sir Keir and himself had “repeated” Mr Johnson’s slurs.
But Conservative peer Lord Lilley, a former Cabinet minister, said “we’re all getting a bit precious about this”.
“Both sides are saying the person at the top of the organisation is responsible for what happens further down … both sides should probably apologise and stop making personal remarks,” he told BBC Newsnight.
Sir Keir apologised while director of public prosecutions in 2013 for the CPS having failed to bring Savile to justice four years earlier.
There is no evidence that Sir Keir had any personal role in the failure to prosecute the man, one of Britain’s most egregious sex offenders, before his death in 2011.