Downing Street staff regularly broke Covid rules and engaged in a "pantomime" to stop their behaviour becoming public, the inquiry into Boris Johnson's conduct has been told.
In a written submission to the inquiry one No.10 official said the building's security team sent around operational notes telling staff to be "mindful of the cameras outside".
The evidence submission, which was sent to the committee on 7 February this year, says the notorious "Wine Time Fridays" drinking events in the press office continued "throughout" the pandemic with no social distancing.
The drinking sessions were "calendared weekly events in our Outlook diaries starting at 4pm" on Fridays and staff who questioned whether masks should be worn were told there was "no point".
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The whistleblower told the inquiry that there was a "wider culture of not adhering to any rules", and that "No.10 was like an island oasis of normality".
The revelations are part of a dump of internal documents made public by the privileges committee as part of their inquiry into Mr Johnson's conduct.
"During the pandemic, No.10, despite setting the rules to the country, was slow to enforce any rules in the building," the evidence from the official says.
"The press office Wine Time Fridays continued throughout, social distancing was no enforced, and mask wearing was no enforce.
"I was once enquired to [redacted] in March 2020, [redacted], whether we should be wearing masks and was told that the science advice was that there was 'no point' and had 'very little effect on the spread of Covid'.
"This was part of a wider culture of not adhering to any rules. No.10 was like an island oasis of normality. Operational notes were sent out from the security team to be mindful of the cameras outside the door, not to go out in groups and to social distance, it was all a pantomime."
The submission continued: "Birthday parties, leaving parties and end of week gatherings all continued as normal. Those responsible for the leadership of No.10 failed to keep it a safe space and should have set rules from the start that these gatherings should not continue."
The Downing Street official, who is not being named by the committee, added that it was "only more than a year into the Pandemic" that NO.10 set up a one way system and desk divider screens to try and mitigate the spread of the virus inside the building.
BBC Panorama previously reported howe one of building's security team was mocked when they tried to stop a party in full flow at No.10.
At last count more than 50 people were issued with Fixed Penalty Notice fines for breaching lockdown rules in Downing Street during the pandemic.
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