Rule breaking Christmas party for Shaun Bailey’s mayoral campaign took place last December

Conservative aides threw a separate party at the Westminster headquarters during coronavirus restrictions last December, the party have admitted, amid the fallout over the alleged 18 December Christmas bash in Downing Street.

The event, organised by Shaun Bailey’s mayoral campaign, took place on December 14 while the capital was in Tier 2 restrictions - when no mixing of households indoors was allowed apart from support bubbles.

According to the Times, the “raucous” party took place in the HQ’s basement and was attended by No 10 aides and featured dancing and wine-drinking into the early hours.

A Conservative party spokesperson confirmed the event took place, but did not say whether last year's London mayoral candidate was there.

Watch the leaked video, obtained by ITV News, showing senior Downing Street staff joking about the December 18 party - days after it's alleged to have taken place

The spokesperson said: “Senior CCHQ (Conservative Campaign Headquarters) staff became aware of an unauthorised social gathering in the basement of Matthew Parker Street organised by the Bailey campaign on the evening of December 14. “Formal disciplinary action was taken against the four CCHQ staff who were seconded to the Bailey campaign”.

The further damaging details emerged as Labour urged police to reopen an investigation into allegations staff broke coronavirus rules at the event in No 10, saying it was “implausible” for the Met Police to suggest there is insufficient evidence to investigate.

Allegra Stratton became the first casualty of the affair when she tearfully announced her resignation after ITV News revealed a video of her and other advisers joking about Covid restrictions just days after the gathering is alleged to have happened on December 18.

'I will regret those remarks for the rest of my days' says Ms Stratton after video emerges

But Prime Minister Boris Johnson’s attempt to apologise and move on from the row, by tasking Cabinet Secretary Simon Case with undertaking an investigation, appeared to have failed as details continued to emerge.

Indeed, Mr Johnson only apologised for the video of staff laughing and didn't admit the party actually happened.

The Metropolitan Police acknowledged it had received “a significant amount of correspondence” relating to the alleged breaches in No 10 in the run up to Christmas last year but said they do not “provide evidence of a breach” of Covid rules.

“Based on the absence of evidence and in line with our policy not to investigate retrospective breaches of such regulations, the Met will not commence an investigation at this time,” it added.

But the force did leave open the possibility of further inquiries by saying it would consider “any evidence” that emerges in the Case inquiry.

ITV News UK Editor Paul Brand reported on the latest developments around the alleged No.10 party scandal which forced the resignation of Allegra Stratton

Shadow health secretary West Streeting said the Met should be “knocking on doors, taking statements and investigating people in No 10 in the way they would my constituents or anyone else in the country”. “It seems implausible for the Metropolitan Police to argue there is no evidence that parties took place,” he told reporters. “They’ve got to pursue this investigation without fear or favour and treat the Prime Minister and his staff as they would treat anyone else. It can’t be one rule for the Prime Minister and another for everyone else”.

Meanwhile, Downing Street did not comment on a separate report in the Times that Dan Rosenfield, then Mr Johnson’s incoming chief of staff, took part in the December 18 party while London was under Tier 3 restrictions.

The Prime Minister has repeatedly insisted the rules were followed that night but apologised over the impression made by leaked footage of No 10 staff joking about Covid restrictions.

Mr Johnson has also been forced to deny allegations, including from senior Conservative William Wragg, that his announcement of Plan B Covid restrictions was a “diversionary tactic” from the scandal.

The Prime Minister was not firm on the Cabinet Secretary's investigation going beyond just reviewing the events of December 18.

He told a presser Mr Case may “look at other things”, among the myriad of other alleged gatherings in Downing Street over the festive period last year.

The education secretary apologised for another party - confirmed to have happened at the Department of Education - but said staff had "gathered together" and denied it was, in fact, a party.

Former Scottish Conservative leader, Baroness Ruth Davidson, expressed her anger at the recent events, Tweeting: "None of this is remotely defensible".

Scottish Tory leader Douglas Ross said Mr Johnson should quit if he was found to have misled Parliament.

“If he knew there was a party, if he knew it took place, then he cannot come to the House of Commons and say there was no party,” he told Sky News.

Tory peer and former Conservative Party chairwoman Sayeeda Warsi has called on those present at the alleged Christmas party to resign.