Now a photograph of Mr Bailey, surrounded by aides, including millionaire donor Nick Candy, has come to light, prompting him to stand aside as the London Assembly’s policing and crime committee chairman.
The image, published by the Mirror, shows Mr Bailey surrounded by revellers in Christmas jumpers and party hats, and features a buffet, with party-goers raising glasses of wine.
It comes amid intense pressure on the government following revelations of several lockdown busting parties taking place in No 10 last Christmas, including a festive quiz attended by the prime minister.
A Shaun Bailey campaign spokesperson said: “On the evening of 14 December 2020, at the end of the working day, the campaign hosted a post-work event to thank campaign staff for their efforts over the course of the year.
“This was a serious error of judgement and we fully accept that gathering like this as that time was wrong and apologise unreservedly”.
While a GLA Conservative group spokesperson said: "Shaun Bailey AM has today stood aside as Chairman of the London Assembly’s police and crime committee.
"He does not want an unauthorised social gathering involving some former members of the London mayoral campaign team last December to distract from the committee’s important work holding the mayor of London to account.
"He will continue to speak up for Londoners who no longer feel safe in our city and push for a strategy to tackle the disproportionate level of crime in London’s black community."
Transport secretary Grant Shapps told the BBC Radio 4 Today programme: “That picture seems absolutely unacceptable. I couldn’t see my own family at this time last year.
“I should say it was not authorised by Conservative HQ. There were four people on secondment from the party and they had each been disciplined prior to seeing that picture.
“I don’t want to prevaricate about this. Many of us were going to great lengths this time last year, including in my family where I thought I may never see my father again.
“Whatever further action needs to be taken, will be taken.”
While Sadiq Khan told BBC Radio London: “I’m shocked, I’m surprised. I saw the photograph yesterday and I couldn’t believe it.
“The platter of food… this time last year the vast majority of us, all decent Londoners, were doing the right thing, making huge sacrifices and lo and behold you’ve got others having parties and so forth.
“I’m afraid it’s only a matter of time before he’s got to quit from the Assembly. It’s inevitable he’ll have to quit from the Assembly.
“I don’t see how he can carry on.”
Mr Bailey, who stood against Mr Khan in the 2021 London mayor race, is yet to comment.