Covid guidance was likely broken every day inside Downing Street during the pandemic, according to the second most senior civil servant in the country at the time.
Helen MacNamara said "hundreds" of Whitehall officials, and probably ministers as well, had breached the government's own rules during the pandemic.
MacNamara, who was deputy cabinet secretary, made the stunning revelation as she gave evidence to the Covid Inquiry.
“I would find it hard to pick one day when the regulations were followed properly inside that building,” she said.
MacNamara, who has now left the civil service, said the only event where the guidance was followed “to the letter” was the weekly Cabinet meeting.
“And everybody moaned about it and tried to change it repeatedly,” she said.
“So I know how exceptional it was to really, really, really properly follow the guidance.”
Referring to the birthday party for Boris Johnson which led to the former prime minister and Rishi Sunak being fined, she said: "When the police ... said that was the wrong side of the line, I’m certain that there are hundreds of civil servants and potentially ministers who in retrospect think they were the wrong side of that line.”
MacNamara served as deputy cabinet secretary from 2020 to 2021 and played a key role in the government’s response to Covid.
She was fined by police for attending a rule-breaking drinks party on June 18, 2020, in the Cabinet Office.
MacNamara told the inquiry it “shouldn’t have happened” and that the public were “rightly offended”.
In her written evidence to the inquiry, MacNamara also recounted a meeting with senior No.10 staff on March 13, 2020.
“I think we are absolutely fucked,” she warned. “I think we are going to kill thousands of people.”
MacNamara also hit out at the “toxic culture” in No.10 with people being subjected to “violent and misogynistic language”.
The inquiry revealed yesterday that Dominic Cummings, Boris Johnson’s former chief of staff, once referred to MacNamara as a “c**t” in a WhatsApp group.