London, UK - The office of UK Prime Minister Boris Johnson on Friday apologized to the Queen after it emerged boozy staff parties were held in his official residence and workplace the day before Prince Philip's funeral last year.

Two gatherings took place at Johnson's Downing Street office, with the prime minister's former director of communications James Slack apologizing for the "anger and hurt" one of the events – a goodbye party held for him – had caused.

A spokesperson for the prime minister said: "It is deeply regrettable that this took place at a time of national mourning and No 10 has apologized to the Palace. You heard from the PM this week, he's recognized No 10 should be held to the highest standards, and take responsibility for things we did not get right."

The day after the events on April 16, 2021, the queen attended her husband Philip's funeral wearing a face mask and socially distanced from her family at Windsor Castle, in line with Covid-19 restrictions.

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The prime minister's spokesman said Johnson was at his country residence Chequers on April 16 and had not been invited to the events.

Asked why No 10 had apologized rather than Johnson himself, his spokesman said: "Well, again, the prime minister said earlier misjudgments have been made and it's right people apologize, as the PM did earlier this week. It remains the case that I can't prejudge the inquiry, which you know is ongoing, which has been led by Sue Gray, but we acknowledge the significant public anger, it was regrettable this took place at a time of national mourning."

It is understood the apology to Buckingham Palace had been delivered via a telephone call through official channels.

The Labour Party's Keir Starmer, the leader of the opposition, said Johnson should also be offering the queen his resignation.

He said: "The Conservatives have let Britain down. An apology isn't the only thing the prime minister should be offering the palace today. Boris Johnson should do the decent thing and resign."

Slack, who until last year was Johnson's director of communications, had apologized on Friday morning for the "anger and hurt" his leaving party had caused.

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Now deputy editor-in-chief of The Sun newspaper – which was notably muted in its coverage of the scandals – Slack said he took "full responsibility" and was "deeply sorry."

At the time of the two newly-reported gatherings on April 16, government guidance said: `"You must not socialize indoors except with your household or support bubble. You can meet outdoors, including in gardens, in groups of six people or two households."

It brings the total number of parties or gatherings alleged to have happened across departments of the British government during the restrictions to 14.

On Wednesday, Johnson apologized for attending a "bring your own booze" party in the Downing Street garden in May 2020, during the first coronavirus lockdown, but insisted he believed it was a work event and could "technically" have been within the rules.

Members of the government urged Johnson's critics to wait for the findings of senior official Sue Gray's inquiry before passing judgment after Conservative MPs began publicly calling for him to quit.