Insiders who attended events at Downing Street during lockdown have told the BBC how staff crowded together and sat on each other’s laps and how party debris was left out overnight.
For the first time, insiders who were at some of the events have told BBC Panorama in detail what they saw.
They describe arriving for work the morning after a get-together to find bottles lying around parts of the building, bins overflowing with rubbish and empties left on the table.
They also tell of events with dozens of staff crowded together, and parties going so late that, on occasion, some ended up staying in Downing Street all night.
And they say staff mocked others who tried to stop what was going on.
The prime minister’s official spokesman said that Boris Johnson took revelations about what happened in Downing Street during lockdown “very seriously”.
He said that the interim report by Sue Gray “raised some of these challenges” and that “wholesale changes” in how No. 10 operated were made as a result, adding there were “further changes to come”.
The accounts come a day before the senior civil servant Ms Gray is expected to deliver her report on lockdown parties in No 10.
Last week, the Metropolitan Police concluded its own investigation into rule-breaking, after issuing 126 fines – including one for the prime minister for attending a birthday party in June 2020.
However, both the police and the prime minister are facing fresh questions after ITV News obtained pictures believed to show the prime minister at a leaving party for his communications chief Lee Cain on November 13, 2020.
Speaking anonymously, three insiders have opened up about a world behind No. 10’s famous front door where the lockdown rules the country was living by were routinely ignored, and socialising was regular, with, they felt, the prime minister’s implicit permission.
One staffer describes director of communications Lee Cain’s leaving do, the event on November 13, 2020, where the prime minister has been pictured raising a glass, but for which he has not been fined.
Others have been judged to have broken the law for being there and received penalties.
Johnson attended and made a speech to thank Cain, but as the party developed, “there were about 30 people, if not more, in a room. Everyone was stood shoulder to shoulder, some people on each other’s laps . . . one or two people.”
At the party on the eve of Prince Philip’s funeral on 16 April 2021, they portray a “lively event . . . a general party with people dancing around”.
The gathering becoming so loud that security guards in the building told them to leave the building and go into the No. 10 grounds.
“So everyone grabbed all the drinks, the food, everything, and went into the garden,” one source says.
“We all sat around the tables drinking. People stayed the night there.”
They now concede what went on was “unforgivable”.