Angela Rayner was with Keir Starmer on the night a photo was taken of him holding a beer during lockdown, Labour have confirmed.
Party sources blamed a “genuine mistake” made “in good faith” after an official initially denied the deputy leader was there in April 2021.
Ms Rayner and the Labour leader were both at the Miners’ Hall in Durham on the night of April 30 for local election campaigning.
They each appeared separately from the venue on an online campaign broadcast for Labour members, with Ms Rayner quoting the Durham miners’ motto: “The past we inherit - the future we build”.
Shortly afterwards, Sir Keir stopped for pizza and a beer with party workers - where he was, now infamously, filmed through the window.
Labour insist no Covid rules were broken at the gathering by either of the two chiefs. Durham Police examined the incident in February and decided to take no further action.
Covid laws at the time banned indoor gatherings of different households, but gatherings “reasonably necessary for work” were exempt.
A Labour spokesman said: “ Keir Starmer was in the workplace, meeting a local MP in her constituency office and participating in an online Labour Party event. They paused for food as the meeting was during the evening. No rules were broken.
"There is simply no comparison between standing in a kitchen having something to eat between meetings, with multiple, flagrant rule breaking drinks parties at the heart of Government, dismissed by lies at the despatch box and resulting in an apology to the Queen."
Keir Starmer today said it made “absolutely no difference” whether Ms Rayner was there because the gathering followed the rules.
He added No10 was “probably the most fined workplace in the whole United Kingdom”, saying: “Now I know what’s going on here. We’re a few days away from local elections and Conservative MPs are trying to throw as much mud as possible.
“What I’d suggest is that they focus on the issue that is burning across Scotland, across the rest of the United Kingdom, which is the cost of living crisis. Because this week in their pay packets people have realised that the government’s tax has left them with even less money than they had before, in the middle of a cost of living crisis.”
A Labour official initially denied to the Daily Mail that Ms Rayner was there. Tory MP Brendan Clarke-Smith told the newspaper: “For all their sanctimony about honesty and transparency, it's plain to see that Labour have not told the truth about Keir Starmer's lockdown drinks party.
“Why would they lie about Angela Rayner's presence if they thought the event was legal?”
It’s understood the initial denial was a mistake and the official was not in possession of all the facts at the time.
It comes after Durham Police spoke out to insist they had not reopened the investigation into Sir Keir after a message to Tory MP Richard Holden was widely misread. Instead, cops are looking at the MP's concerns.
Mr Holden told Durham Police he had discovered a “concerning new piece of evidence”, that members were invited to a quiz on the night.
A Labour source insisted the quiz was on Zoom via members’ living rooms, wasn’t in the building where Sir Keir was, and he didn’t take part.
Mr Holden, who is demanding police reopen the case, stopped for a group curry himself for work purposes days earlier.
It’s understood the MP whose office was used, Mary Kelly Foy, apologised to Mr Holden this week after angrily confronting him over the row.
Witnesses claimed she “shouted” at Mr Holden on the Commons terrace on Tuesday night. Mr Holden said her behaviour was “utterly unacceptable”.
Meanwhile, the Daily Mail revealed Keir Starmer was given a birthday card and two cakes in his office on his birthday in September 2020.
There was no suggestion this broke any laws, because the first lockdown had been axed by this point.
The Labour leader’s birthday was on September 2, a few weeks before SAGE - and then Sir Keir - recommended a new lockdown due to rising cases.
Guidance did however advise people not to “hold or attend celebrations” at close quarters.
Defence Secretary Ben Wallace suggested there was a double standard between Sir Keir and Boris Johnson, who was being investigated by police over six separate parties during legal lockdowns.
He told the Mail: “A consistency of the application of the law, that's what we all deserve - whether we're in London or whether we're in Durham.”
But Shadow Chief Secretary to the Treasury Pat McFadden hit back, telling Sky News: “The police have already looked at this in Durham and they have found nothing to take action on.
“People are trying to draw some equivalence to this but the police have already looked at it and that has been their conclusion.
“I simply don’t believe that this is equivalent in any way to a series of parties, ‘bring your own booze’, booze being brought in by the suitcase, with Abba singing Winner Takes It All in the background.
“They want people to think it’s all the same, so no scandal matters and that is a bad place for us to go.”
Durham Police said: "Earlier this year, Durham Constabulary undertook a review of video footage recorded in Durham on April 30, 2021.
"We stated that we did not believe an offence has been established in relation to the legislation and guidance in place at the time the footage was taken and would therefore take no further action in relation to the matter.
"We have since received a number of further communications relating to this matter and will now consider the contents of those communications and respond in due course.
"For clarity, Durham Constabulary is not currently investigating this incident."