British Prime Minister Boris Johnson's authority took yet another hit on Friday (January 14), when his office had to apologize to Queen Elizabeth for a party held late into the night at his Downing Street residence.

While she mourned her husband Prince Philip, who was buried the next day.

Indoor mixing was banned at the time.

Almost daily revelations of staff social gatherings during lockdowns have plunged Johnson's premiership into crisis.

Some were held when ordinary people could not bid farewell in person to dying relatives.

The Daily Telegraph reported that two drinks parties were held inside Downing Street last April 16.

It said staff bought a suitcase full of alcohol from a nearby supermarket, spilled wine on carpets and broke a swing belonging to Johnson's son.

The next day, the 95-year-old queen sat alone, in strict compliance with the rules, at Philip's funeral service at Windsor Castle.

For many Britons, her solitary, masked figure became a defining image of the grief wrought by the pandemic.

Johnson was at his country residence and wasn't invited to the party, his spokesman said.

But, as well as his opponents calling on him to resign, a small but growing number of Conservatives have turned against him.

The Conservative-leaning Telegraph said some 30 letters of no confidence have been written to the chairman of the party's "1922 Committee".

Fifty-four letters would trigger a leadership challenge.

Explanations by the prime minister, who built a political career out of flouting norms, have ranged from denying rules were broken to understanding public anger.

This was Foreign Minister Liz Truss on Friday:

"He was very clear that mistakes have been made... He has apologized and I think we now need to move on and talk about how we are going to sort out issues..."

British police say they won't investigate the gatherings unless an internal government inquiry finds evidence of potential crimes.