The UK government apologised Friday to Queen Elizabeth II, after revelations Prime Minister Boris Johnson's staff broke coronavirus restrictions by partying on the eve of Prince Philip's funeral.

"It is deeply regrettable that this took place at a time of national mourning and Number 10 (Downing Street) has apologised to the palace," Johnson's spokesman told reporters.

The message to the 95-year-old head of state is understood to have been sent through official channels by telephone and not personally sent by Johnson, who is under growing pressure to quit after a slew of similar allegations.

Public anger has mounted at the revelations, because of strict rules in place on social mixing at the time
Public anger has mounted at the revelations, because of strict rules in place on social mixing at the time AFP / Tolga Akmen

He has so far tried to weather the storm of public and political outrage, apologising in parliament this week for attending one of the gatherings in May 2020 but insisting it was a work event.

Although Johnson was not at either of two Downing Street parties nearly a year later -- on April 16, 2021, as the Queen prepared to bury her husband of 73 years -- it takes the scandal to another level, chipping away further at Johnson's authority.

Prince Philip's funeral at Windsor Castle was limited to just 30 guests due to government Covid rules, forcing the Queen to sit alone in a church pew to mourn.

UK Prime Minister Boris Johnson has faced a slew of allegations of lockdown-breaching parties at his Downing Street office and residence
UK Prime Minister Boris Johnson has faced a slew of allegations of lockdown-breaching parties at his Downing Street office and residence AFP / Tolga Akmen

A similar number of Johnson's staff held separate boozy bashes just hours earlier, with music, dancing and alcohol allegedly bought at a supermarket and smuggled into Downing Street in a suitcase.

Johnson, who is currently isolating due to a close family member contracting coronavirus, was at his official country residence at the time, his spokesman said.

He declined to say whether Johnson had been aware of the parties, insisting an internal probe must establish all the facts around the various "partygate" claims.

Brexit supporter Andrew Bridgen said he had written a vote of no confidence letter in Johnson
Brexit supporter Andrew Bridgen said he had written a vote of no confidence letter in Johnson AFP / Niklas HALLE'N

They include a new report in The Daily Telegraph that the former head of the Cabinet Office Covid taskforce, Kate Josephs, held a "boozy" leaving party on December 17.

She apologised in a statement.

All three main opposition parties have demanded Johnson's resignation. Five of his own Conservative MPs have publicly called for him to quit.

Finance minister Rishi Sunak is widely tipped to take over if Johnson quits or is forced out in a leadership contest
Finance minister Rishi Sunak is widely tipped to take over if Johnson quits or is forced out in a leadership contest AFP / Daniel LEAL

Andrew Bridgen, a previously loyal supporter, on Friday became the latest Tory MP to confirm he had submitted a no confidence letter in Johnson to a powerful committee of rank-and-file Conservative MPs.

If 15 percent, or 54, of the 360 Conservative MPs in parliament do the same, it will trigger an internal leadership contest -- if Johnson opts not to quit.

The Daily Telegraph, normally a staunch supporter of Johnson, reported as many as 30 MPs had already sent letters.

Bridgen -- a staunch supporter of Brexit, which swept Johnson to power in 2019 -- wrote in the newspaper there was currently "a moral vacuum at the heart of our government".

Most cabinet members have rallied around the prime minister but the backing from potential successors such as finance minister Rishi Sunak has been distinctly lukewarm.

Johnson's former communications director, James Slack, apologised for the "anger and hurt" his April 16 leaving party had caused.

Slack, now deputy editor-in-chief at The Sun tabloid, said he took "full responsibility" and was "deeply sorry".

The party reportedly merged with another event marking the departure of one of Johnson's personal photographers.

Government guidance at the time outlawed socialising except with your household or support bubble. That saw thousands of families unable to visit loved ones who were sick or dying with Covid, or even attend their funerals.

Angela Rayner, deputy leader of the main opposition Labour party, and others seized on the revelations, arguing they showed a culture of double standards at the heart of government.

"The Queen sat alone in mourning like so many did at the time with personal trauma and sacrifice to keep to the rules in the national interest," Rayner said.

"I have no words for the culture and behaviours at Number 10 and the buck stops with the PM."

Fran Hall, from the Covid-19 Bereaved Families for Justice group, said: "For the people running the country to do it and then lie about it, shows a complete disdain for the general public."

Voters in Johnson's northwest London constituency were largely unsympathetic. "I think he should resign," John Taylor, 80, who voted for Johnson in 2019, told AFP.

"He let people down, particularly people who in some way have suffered through this Covid."

Veronica Machu, another traditional Tory voter, agreed "people are angry" locally, but predicted Johnson would "keep saying sorry" and attempt to cling on.

A poll by YouGov in The Times newspaper gave Labour a 10-point lead over the Tories, its biggest margin since 2013, and said six out of 10 voters believe Johnson should resign.