Mr Johnson said he thought the party was a “work event” but added that “with hindsight I should have sent everyone back inside”.
Mr Johnson insisted that nobody had told him a party at Downing Street would break rules he himself had set.
He appeared in a major broadcast interview on Tuesday (18 January) and apologised multiple times for the “misjudgments that were made”.
However, he continued with his defence that he had thought a “bring your own booze” party held in the No 10 garden on May 20, 2020 had been a work event.
The Prime Minister also denied that he had been warned about the party in advance.
Mr Johnson’s former chief aide Dominic Cummings has thrown that claim into doubt after he said he would “swear under oath” that the Prime Minister was told about the bash.
The Conservative party leader also faced a defection over the scandal, with Bury South MP Christian Wakeford joining Labour.
Pressure has been mounting on the Prime Minister to resign with several high-profile Tories calling for him to go - and a so-called ‘pork pie plot’ launched by several MPs to oust him.
Here we look at the Tory MPs who have publicly called for Mr Johnson to resign.
List of Conservative MPs who have called for Boris Johnson to resign
The Scottish Conservative leader and MP for Moray has called for the Prime Minister to quit.
He has also been joined by all 31 Tory MSPs in calling for Mr Johnson’s resignation, according to reports.
Mr Ross confirmed he had sent a letter of no confidence to the chairman of the 1922 Committee of backbench Tory MPs, Sir Graham Brady.
He said Mr Johnson’s position was “no longer tenable” and “I don’t think he can continue as leader of the Conservatives”.
Sir Roger Gale
The Conservative North Thanet MP told the PA news agency “you don’t have bring-a-bottle work events in Downing Street, so far as I’m aware.”
He added: “I think the time has come for either the Prime Minister to go with dignity as his choice, or for the 1922 Committee to intervene”.
Mr Wragg, a vice-chairman of the 1922 Committee and MP for Hazel Grove, told BBC Radio 4’s PM programme: “The Prime Minister’s position is untenable and I don’t believe it should be left to the findings of a civil servant to determine the future of the Prime Minister, and indeed, who governs this country.
“I think it is for the Conservative Party – if not the Prime Minister in fact – to make that decision.”
The MP for Romsey and North Southampton told ITV’s Peston the Prime Minister had “put himself in an impossible position”.
She said Mr Johnson “did a fantastic job” at the 2019 election, but added: “Now regretfully, he looks like a liability, and I think he either goes now, or he goes in three years’ time at a general election, and it’s up to the party to decide which way around that’s going to be.
“I know my thoughts are that he’s damaging us now.”
The Conservative MP for North West Leicestershire has publicly announced that he had submitted a letter of no confidence in the Prime Minister on Thursday (13 January) night.
He was the fifth MP to confirm that they had written to Sir Graham, the chair of the 1922 Committee, calling for a vote on the PM’s future as head of the party.
Mr Bridgen told BBC Newsnight: “With a heavy heart, I have written a letter to Sir Graham Brady indicating that I have no confidence in the Prime Minister and calling for a leadership election.”
The former children’s minister wrote in a Facebook post that Mr Johnson’s position had become “untenable” and that his “resignation is the only way to bring this whole unfortunate episode to an end”.
Apologising for the “great hurt” caused to his constituents by the allegations, the East Worthing and Shoreham MP added: “Frankly the issue for me is not how many sausage rolls or glasses of prosecco the Prime Minister actually consumed.
“The reason for my conclusion in calling for him to stand down is the way that he has handled the mounting revelations in the last few weeks.
“Obfuscation, prevarication and evasion have been the order of the day when clarity, honesty and contrition was what was needed and what the British people deserve.”
The former Brexit secretary called for Mr Johnson’s resignation during PMQs, telling him “in the name of God, go.”
Mr Davis said he has defended the Prime Minister for weeks from angry constituents, reminding them of the “successes of Brexit”.
He then told the House of Commons: “I expect my leaders to shoulder the responsibility for the actions they take.
“Yesterday, he did the opposite of that so I will remind him of a quotation which may be familiar to his ear – Leopold Amery to Neville Chamberlain: You have sat too long here for any good you have been doing. In the name of God, go.”
Other high-profile Conservatives who have called for Boris Johnson to resign
Baroness Sayeeda Warsi
The former co-chairman of the Conservative Party, who served in the coalition government, has called for Mr Johnson to go.
She tweeted: “Every minister, parliamentarian & staffer at any #downingstreetparty must resign NOW. No ifs no buts.
“The rule of law is a fundamental value - the glue that holds us together as a nation. Once that is trashed by those in power the very essence of our democracy is at stake.”
Baroness Ruth Davidson
The former leader of the Scottish Conservative Party backed the calls of her successor, Mr Ross, for the Prime Minister to go.
She tweeted: “A tough call to make. But the right one.”
Ms Davidson added: “Nobody needs an official to tell them if they were at a boozy shindig in their own garden.
“People are (rightly) furious. They sacrificed so much – visiting sick or grieving relatives, funerals. What TF were any of these people thinking?”
How many no-confidence letters have been sent to the 1922 committee?
The future of Mr Johnson’s premiership will depend on how many letters of no confidence are submitted by Tory MPs to Sir Graham.
The 1922 Committee chairman will not reveal how many letters he has received until the figure of 15% of MPs is reached - which will trigger a confidence vote.
With the current parliamentary make up this would mean 54 letters.
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