Boris Johnson led the celebrations at a lockdown leaving do, it is claimed.
He allegedly poured the drinks to toast his aide Lee Cain, and had often urged staff to “let off steam”.
Labour’s Angela Rayner said Mr Johnson had “demeaned his office”.
No10 sources denied that the PM had organised Mr Cain’s leaving do.
It's claimed Boris Johnson encouraged his staff to socialise and “let off steam” at Downing Street drinks bashes during lockdown.
The Prime Minister is braced for more fines for attending lockdown parties, including the leaving bash for his former director of communications Lee Cain in November 2020.
That event began with the press office having drinks to round off the week, but turned into a party once Mr Johnson arrived and started pouring drinks for everyone.
Sources confirmed to the Daily Mirror that the official taxpayer-funded photographer was present throughout – taking pictures of the PM breaking his own lockdown rules.
The photos were later handed to police.
Downing Street insiders have also told the Mirror how the PM would often see staff “sitting there drinking” as he went to his flat.
Even though indoor socialising was forbidden under lockdown rules at the time, the Prime Minister did nothing to break up the gatherings.
The source said: “He would come in and say, ‘Hello everyone, had a hard week? Letting off some steam? Oh great’. The idea that he didn’t know there were drinks is total nonsense. If the PM tells you to ‘let off steam’, he’s basically saying this is fine.”
One of Britain’s most respected constitutional historians yesterday branded Mr Johnson a “rogue Prime Minister unworthy of the Queen”.
Peter Hennessy, who sits in the House of Lords, said the Prime Minister was “sweeping aside all the conventions” in an “assault on the institutions of the state”.
The usually mild-mannered cross-bench peer accused Mr Johnson of “sullying” his office “like no other, turning it into an adventure playground for one man’s narcissistic vanity”.
He said: “The decencies and probities and conventions of public life are not enough to constrain the ego that is currently filling No10.”
Damningly for the Prime Minister, Lord Hennessy claimed Mr Johnson “must have knowingly misled” Parliament when he claimed repeatedly that the lockdown rules were followed at all times.
On Tuesday, Speaker of the House of Commons, Lindsay Hoyle, is expected to allow MPs to vote on whether to hold an investigation into claims the Prime Minister misled Parliament when he told MPs he had not broken any lockdown rules.
On Wednesday, Mr Johnson faces a vote on whether he will be referred to the Parliamentary Privileges Committee. If he is found to have broken the rules, Mr Johnson could be suspended from Parliament for a contempt of privilege.
Labour ’s Deputy Leader Angela Rayner blasted the PM over the allegations about the party for Mr Cain. She said: “If the latest reports are true, it would mean that not only did the Prime Minister attend parties, but he had a hand in instigating at least one of them.
“He has deliberately misled the British people at every turn. The Prime Minister has demeaned his office.”
Sources told the Mirror that Mr Johnson had joined the No10 press team on November 13, 2020, the day Mr Cain and the Prime Minister’s former top aide Dominic Cummings left Downing Street. Mr Johnson “poured the drinks” – including for himself – and chatted to his aides before toasting his departing spin chief and posing for photographs.
Another insider told The Sunday Times: “Boris came fumbling over, red box in tow, and he gathered the staff around the press office table, which did have bottles of alcohol on it. He said he wanted to say a few words for Lee and started pouring drinks for people and drinking himself. He toasted him.”
Mr Johnson later headed upstairs to the flat where his wife Carrie was alleged to have been hosting a party with friends to celebrate Mr Cummings’ departure.
Downing Street sources did not dispute the description of Mr Cain’s leaving do, but denied that the Prime Minister had organised it.
Mr Johnson is understood to have been present for at least six of the 12 events being investigated by the Metropolitan Police for breaking Covid rules.
He, wife Carrie and Chancellor Rishi Sunak were all fined by the Met Police for breaking lockdown laws with a gathering on June 19, 2020, celebrating the Prime Minister’s 56th birthday.
The Prime Minister is expected to make a statement to Parliament tomorrow about the fine, where he is set to apologise for breaking the rules, but insist he was not aware he had done so.
Mr Johnson will this week continue his attempts to get back on the front foot after a week where the Partygate scandal came back to haunt him.
The PM plans to meet all Tory MPs tomorrow evening for a “clear the air” discussion designed to shore up support as they return to Westminster after the Easter break.
He will then go to India for a long-delayed trip to discuss defence, including the Ukraine conflict, and trade with PM Narendra Modi.
Mr Johnson’s allies have defended his police fine by saying that not all crimes are as serious as each other, murder not being the same as manslaughter.
One of his supporters even claimed someone had not “really endangered life” if they were caught four times just over the speed limit.
That suggestion was ridiculed by former Man United and England footballer Gary Neville, who pointed out that people fined for speeding four times in a certain period lose their licence and are banned from driving.
Cabinet minister Jacob Rees-Mogg defended the Prime Minister, saying that Mr Johnson had not misled the House of Commons – which is traditionally a sackable offence – with his repeated denials of lockdown-busting parties.
He said: “I think that the Prime Minister spoke to Parliament in good faith. I think that when you hear what happened on the party for which he has been fined, many people would think that they were in accordance with the rules.
“They were meeting people they were with every day, who happened to wish them a happy birthday, because that was the day it was.
“Now the police have decided otherwise and the police have an authority.
“But he wasn’t thinking something irrational or unreasonable, that that was within the rules.”
