Boris Johnson is to face a parliamentary inquiry into claims he misled MPs about lockdown-busting parties in Downing Street.
MPs unanimously passed a Labour motion calling for the privileges committee probe to take place once the police have finished their own investigations into the partygate affair.
It is thought to be the first time a sitting prime minister has faced such an investigation.
The move came after the government performed a dramatic U-turn by ditching a bid to kick a decision on the inquiry into the long grass.
The prime minister has been accused of misleading parliament in December, when he insisted Covid rules had been followed in Number 10 at all times.
Since then, the Metropolitan Police have issued more than 50 fixed penalty notices for breaches of lockdown laws, including to Johnson himself, his wife Carrie and chancellor Rishi Sunak.
The privileges committee, which has a Conservative majority, will have the power to demand the publication of more than 300 official photographs which are believed to have been taken at various alleged gatherings in Downing Street and Whitehall during lockdown.
The committee’s inquiry also means that the partygate affair is sure to rumble on for months, further damaging the PM.
On another difficult day for Johnson, who is in India on an official visit, influential backbencher Steve Baker became the latest Tory MP to publicly call for him to go.
He told the Commons: “The prime minister now should be long gone. Really, the prime minister should just know the gig’s up.”
Meanwhile, Tory backbencher William Wragg said: “I cannot reconcile myself to the prime minister’s continued leadership of our country and the Conservative Party.”
On Wednesday night, Downing Street had announced that all Tory MPs were being ordered to vote for an amendment which would have delayed any decision on a parliamentary inquiry until after Sue Gray publishes his full report into partygate.
But they were forced to backtrack after it became clear the prime minister would face a major rebellion from his own MPs.
Announcing the climbdown, a No.10 spokesperson said: “The prime minister has always been clear that he’s happy to face whatever inquiries parliament sees fit and is happy for the House to decide how it wishes to proceed today and therefore will not be whipping Conservative MP’s.
“They are free to vote according to how they believe we should move forward on this.
“We tabled an amendment last night because we wanted to be explicit about ensuring Sue Gray is able to complete and publish her report without any further delay, as well as allow the Metropolitan Police to conclude their investigations.
“We now recognise that – in practice – this is almost certainly likely to be the case and therefore we are happy for the Labour motion to go through if that is the will of the House.”
Labour leader Keir Starmer said: “The prime minister has stood before this house and said things that are not true, safe in the knowledge that he will not be accused of lying because he can’t be.
“He has stood at that despatch box and point blank denied rule-breaking took place, when it did.
“As he did so, he was hoping to gain extra protection from our good faith that no Prime Minister would deliberately mislead the House.”
In a bad-tempered interview with Sky News, Johnson insisted he had “nothing, frankly, to hide” from the inquiry.
Pushed on whether the current situation he finds himself in was serious, the PM replied: “Of course, I think it is serious.
“I also think we have massive issues that people expect us to address. I think people want us to get on with the job of taking the country forward.”
But he appeared frustrated with the line of questioning, asking “how many” times Sky’s political editor Beth Rigby would press him on partygate.