Deputy leader Angela Rayner has written to cabinet secretary Simon Case to ask whether he will make inquiries into events held at Downing Street – and refer any violations found onto the Metropolitan Police.
Boris Johnson reportedly gave a speech at a packed leaving do for a senior aide last November when the country was in the midst of the second lockdown.
And members of his No 10 team are said to have held their own festive party in the days before Christmas while London was under tight tier 3 restrictions.
In her letter to the country’s top civil servant, Ms Rayner said it was “difficult to understand” how either event could have been within the rules, and claimed the government was “undermining public health messaging”.
The Labour deputy also asked the cabinet secretary if he would refer any potential breach of the regulations by the prime minister or his staff onto the police.
The Daily Mirror first reported that there was reportedly 40 or 50 people crammed “cheek by jowl” into a medium-sized room at the two events held when strict lockdown curbs where in place.
And multiple other parties were held in Downing Street over the festive period while indoor mixing was banned, according to the latest reports.
Leading barrister Adam Wagner, an expert on Covid restrictions, has said rules were “probably broken” at the 18 December gathering.
Tier 3 restrictions in place in London meant people were not allowed to mix indoors with people outside their household, while guidance for the Christmas period said “you must not have a work Christmas lunch or party”.
Business minister George Freeman claimed on Thursday that he could “absolutely assure you” that Downing Street staff adhered to Covid rules last Christmas.
But the minister conceded he could not get “drawn into who was or wasn’t in the room and who was drinking which cocktail” because he was not in government at the time.
Labour leader Sir Keir Starmer said Mr Johnson was “taking people for fools” after the prime minister claimed to have followed all Covid rules.
On Thursday he tweeted: “Boris Johnson hosted multiple parties when the country was in lockdown over Christmas. Yesterday he claimed that was within the rules. He is taking people for fools.”
The Covid-19 Bereaved Families for Justice group also condemned Mr Johnson over the events held over the festive period. “The first thing the prime minister must do is acknowledge the hurt this has caused, and apologise,” said Safiah Ngah, who lost her father to Covid earlier this year.
No 10 has not denied that parties had taken place but have continued to insist that the gatherings were Covid compliant. “Covid rules have been followed at all times,” said a spokesperson.
Downing Street has urged firms not to cancel Christmas parties and said people are free to kiss whomever they like in a bid to clear up confusion over guidance.
Mr Freeman suggested larger businesses should consider cancelling their staff Christmas parties, while work and pensions secretary Therese Coffey warned against “snogging under the mistletoe”.
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