As No10 party allegations continue to emerge, Boris Johnson and his allies are fighting for his political survival this weekend, reports ITV News Political Correspondent David Wood
The Labour leader told the PM it would be in the "national interest" for him to resign and urged Tories to get "rid of him" if he refuses.
Not only has the prime minister admitted to attending a bash in the garden of Number 10 at the height of the UK's first lockdown in May 2020, but Number 10 was forced to apologise to the Queen for partying the night before Prince Philip's socially distanced funeral.
Sir Keir Starmer, in a speech at the Fabian Society conference, accused Conservatives of running down the health service and the prime minister of being “too preoccupied defending his rule breaking” to turn it around.
It follows a week in which Mr Johnson has faced calls from Tory MPs to resign after he admitted to attending a “bring your own booze” event, which was confirmed to have taken place after ITV News released a leaked email inviting 100 staff to the event.
The email, sent by Mr Johnson's Principal Private Secretary Martin Reynolds, invited staff to "socially distanced drinks" in the Number 10 garden to "make the most of the lovely weather."
That gathering – which the prime minister told the Commons he understood to be a “work event” – and a host of other claims of lockdown rule-breaking in government are currently being investigated by senior civil servant Sue Gray.
Two other parties - also being investigated by Ms Gray - could be just as damaging for the PM, even though he wasn't there, due to the timing of the events - just one day before the Queen attended her husband's funeral socially distanced from her family.
There is no sign that the pressure is easing on the prime minister, explains David Wood
It was confirmed after the prime minister's former director of communications, James Slack, apologised for attending one of the parties, which was held to mark his departure from Downing Street to become deputy editor-in-chief of The Sun newspaper.
No 10 said: "It's deeply regrettable that this took place at a time of national mourning and Number 10 has apologised to the Palace."
"You heard from the PM this week, he's recognised No 10 should be held to the highest standards and take responsibility for things we did not get right."
The latest party revealed to have taken place - leaving drinks for a civil servant who was head of the Cabinet Office's Covid Taskforce - means Ms Gray is now looking into at least nine separate parties.
Kate Josephs, who is now CEO of Sheffield City Council, issued an apology for holding the drinks event on December 17, telling her Twitter followers she is "truly sorry".
While the latest party does not implicate the prime minister directly, it adds to the idea that there was a culture of rule breaking within government while the rest of the country was forced to endure strict restrictions.
And Tory MPs - the only people with the power to remove the prime minister - are growing angrier with each accusation.
Up to 20 MPs are understood to have submitted letters of no confidence in Mr Johnson, however that is well short of the 54 required to trigger a vote on his leadership.
One Tory told ITV News that staff partying before Prince Philip's funeral would be the "nail in the coffin" for the PM.
Downing Street staff brought a suitcase of wine into No10 for leaving parties that took place as the Queen was preparing for her husband's funeral, as Deputy Political Editor Anushka Asthana reports
The Labour leader, answering questions after a speech at the Fabian Society conference in London, said: “What we’ve now got to is a situation where you have a Prime Minister who has lost the moral authority to lead.
“And just when you need, because we are not out of the pandemic, a Government that has that moral authority to lead, we’ve lost it with this Prime Minister.”
He added: “The moral authority matters of course in relation to Covid, but we’ve got other massive challenges facing this country.
“We’ve got a Prime Minister who is absent – he is literally in hiding at the moment and unable to lead, so that’s why I’ve concluded that he has got to go.
“And of course there is a party vantage in him going but actually it is now in the national interest that he goes, so it is very important now that the Tory Party does what it needs to do and gets rid of him.”
Sir Keir set out his “personal crusade” for NHS reform, accusing subsequent Tory-led administrations of allowing the health service to fall into a “critical condition”.
He told the Fabian Society: “Rather than concentrating on getting through the pandemic and bringing down waiting lists, this self-indulgent Tory party is instead having a fight about a leader who they should have known from the start is not fit for office.
“We are witnessing the broken spectacle of a Prime Minister mired in deceit and deception, unable to lead.
“When we left office 12 years ago, the Conservatives inherited a strong NHS.
“Waiting times were the shortest on record. Today, NHS waiting lists are the highest since records began.
“And it is not good enough to blame all this on Covid – this mess has been much longer in the making.
“This government has to bear the responsibility. Why have we got to this point, where the NHS itself is in a critical condition?”