Here is a list of the alleged parties, which in several cases have been admitted to.

Boris Johnson, his wife Carrie, former chief adviser Dominic Cummings, and Mr Johnson's principal private secretary Martin Reynolds were all pictured, in a photograph leaked to The Guardian, sitting around a table in the No 10 garden, with wine and cheese in front of them.

Some 15 other people were also in the photograph, but the Prime Minister has insisted this was a work meeting, saying: "Those were meetings of people at work, talking about work."

The revelation came in an email, leaked to ITV, from Mr Reynolds to more than 100 Downing Street employees asking them to "bring your own booze" for an evening gathering.

Multiple reports have suggested the Prime Minister attended the event with his wife.

According to reports at the time, Mr Johnson gave a leaving speech for Lee Cain, his departing director of communications and close ally of Mr Cummings.

There are allegations that the Prime Minister's then fiancée hosted parties in their flat, with one such event said to have taken place on November 13, the night Mr Cummings departed No 10.

A spokesman for Mrs Johnson has called the claim "total nonsense".

A Treasury spokesperson told The Times a number of staff had come into the office to work on the Spending Review.

They said: "We have been made aware that a small number of those staff had impromptu drinks around their desks after the event."

The Mirror reported that the Prime Minister gave a farewell speech to an aide at the end of November while the lockdown in England was still in place.

Other reports have said the leaving do was for Cleo Watson, a senior Downing Street aide and ally of Mr Cummings.

The DfE confirmed a social event had happened after The Mirror reported former education secretary Gavin Williamson threw a party and delivered a short speech at an event organised at his department's Whitehall headquarters.

A spokesman acknowledged that "it would have been better not to have gathered in this way at that particular time".

A fridge with the capacity for 34 wine bottles is delivered through the back door of No10. According to sources cited by The Mirror, the fridge became necessary for staff's "wine-time Fridays" which were held through lockdown, with the Prime Minister allegedly encouraging the parties to help aides "let off steam".

The regular social gatherings were reported to be particularly popular among staff between autumn 2020 and spring 2020 when staff were "fatigued" with tough Covid restrictions which banned socialising. Mr Johnson was said to have attended a "handful" of these gatherings.

Shaun Bailey apologised "unreservedly" for attending the gathering at Conservative Campaign Headquarters (CCHQ) organised by staff on his campaign team.

"It was a serious error of judgment at a time when Londoners were making immense sacrifices to keep us all safe and I regret it wholeheartedly," he tweeted.

He quit his role chairing the London Assembly's police and crime committee after The Mirror published a picture showing him at the gathering.

The Prime Minister appeared on contestants' screens at the quiz but insisted he broke no rules.

An image published by the Sunday Mirror showed the Prime Minister flanked by colleagues, one draped in tinsel and another wearing a Santa hat, in No 10.

Downing Street admitted Mr Johnson "briefly" attended the quiz after the photographic evidence emerged but insisted it was a virtual event.

The Mirror reported senior civil servants were "boozing and dancing" at the event, allegedly planned by staff from Transport Secretary Grant Shapps' office.

A DfT spokesman said: "Fewer than a dozen staff who were working in the office had a low-key, socially distanced gathering in the large open-plan office after work on December 16, where food and drink was consumed. We recognise this was inappropriate and apologise for the error of judgment."

A number of outlets reported that a gathering was held in the Cabinet Office on December 17.

The Times reported that Cabinet Secretary Simon Case attended the party in room 103 of the Cabinet Office, that it had been organised by a private secretary in Mr Case's team, and that it was included in digital calendars as "Christmas party!".

The Cabinet Office confirmed a quiz took place, but a spokesperson said: "The Cabinet Secretary played no part in the event, but walked through the team's office on the way to his own office."

The former director general of the Government's Covid Taskforce said she was "truly sorry" over an evening gathering in the Cabinet Office for her leaving drinks during coronavirus restrictions days before Christmas in 2020.

Kate Josephs, who is chief executive of Sheffield City Council, said she gathered with colleagues who were in the office that day and added she was co-operating with the probe by senior civil servant Sue Gray.

The claim which kicked off the rule-breaking allegations is that a party was held for Downing Street staff on December 18.

Officials and advisers reportedly made speeches, enjoyed a cheese board, drank together and exchanged Secret Santa gifts, although the Prime Minister is not thought to have attended.

Mr Johnson's spokeswoman Allegra Stratton quit after being filmed joking about it with fellow aides at a mock press conference.

The Telegraph reported that advisers and civil servants gathered after work for two separate events on the Friday night.

They were to mark the departure of James Slack, Boris Johnson's former director of communications, and one of the PM's personal photographers.

Mr Slack, who left his No 10 role to become deputy editor-in-chief of The Sun newspaper, said he was sorry for the "anger and hurt" caused by his leaving do, while Downing Street apologised to the Queen.

The Telegraph quoted a No 10 spokesperson as saying Mr Johnson was not in Downing Street that day and is said to have been at Chequers.

The newspaper reported accounts from witnesses who said alcohol was drunk and guests danced to music, adding that it had been told that around 30 people attended both events combined.