Fresh allegations made by Dominic Cummings of another rule-breaking Downing Street party will be investigated as part of the ongoing Whitehall investigation into claims of other such events.In a blog on Friday, Mr Cummings alleged a party took place in May 2020, around a week after the outdoor drinks gathering the Guardian pictured last year.
Boris Johnson's former top aide said an email was sent out inviting people to a "socially distanced drinks" event which he warned could break Covid regulations.
But the event "definitely happened" despite his protests, the former political adviser said, after he went home for the day.
ITV News Political Editor Robert Peston said it had been confirmed to him Sue Gray, the top civil servant appointed to investigate several parties allegedly held on Downing Street during the pandemic, will expand her investigation to cover Mr Cummings' latest claims.
Mr Cummings said in a lengthy blog there would be an email chain linked to a senior government official Ms Gray could track down.
The government has previously denied that rules were broken on Downing Street during the pandemic.
It is also understood that the garden gathering reported by the Guardian which is said to have taken place five days before the event mentioned by Mr Cummings in his blog, will also be covered by Ms Gray's inquiry.
Mr Cummings also claimed there was a party in the Number 11 flat shared by the PM and his wife Carrie on the evening he left Downing Street for good on November 13, 2020.
"Staff in the press office said they could hear the music playing loudly in the press office below (the press office is directly below the flat)," he said.
He added: "Officials I spoke to in 2021 said to me and others that there were various parties after I left and the PM was aware of them. I have also been told there are other photos of other parties against the rules in 2021, some picturing the PM."
Claims by Mr Cummings add to at least 10 allegations of Covid-rule-breaking carried out by members of the Tory party during the coronavirus pandemic.
Despite the government's denial that rules were broken on Downing Street during the pandemic, a leaked video released by ITV News showed Number 10 staff laughing about attending a Christmas party in 2020.
The video sparked swathes of new allegations and a number of resignations.
Watch Downing Street staff joking about attending a rule-breaking party:
But Mr Cummings has insisted a gathering in the Downing Street garden where staff were pictured with cheese and wine during the first lockdown did not break rules and was not a party.
Mr Cummings himself can be seen in the image.
The former No 10 adviser said: "It is alleged by many that this shows 'a party', 'rule breaking' and so on. This is wrong."
Following meetings that day, he said: "Someone brought a bottle of wine out to the table. It may have been Martin (Reynolds, who is Boris Johnson's principal private secretary) but I think it was the PM himself who went inside as I was packing stuff up and brought out wine.
"We carried on chatting about Covid, about domestic priorities, and about how to sort out the Cabinet Office which had totally collapsed. Shortly after Carrie joined us."
Mr Cummings said that No 10 staff were "encouraged" to meet in the garden between April and August because it was "safer" during the pandemic.
“Those were people at work talking about work," Mr Johnson said.
"Those were meetings of people at work talking about work. This is where I live, it is where I work. Those were meetings of people at work, talking about work," he added.
A Downing Street spokesperson also claimed the gathering was a work meeting and that Mr Johnson went back to his flat at 7pm.
Back in December, the prime minister's spokesperson said: “In the summer months, Downing Street staff regularly use the garden for some meetings.
"On 15 May 2020, the prime minister held a series of meetings throughout the afternoon, including briefly with the then health and care secretary and his team in the garden following a press conference.
“The prime minister went to his residence shortly after 7pm. A small number of staff required to be in work remained in the Downing Street garden for part of the afternoon and evening.”