Downing Street party: Boris Johnson pictured clapping key workers the day after ‘inexcusable’ Number 10 drinks

The Prime Minister participated in "clap for carers" - a weekly event aimed at showing thanks for NHS and other key workers during the Covid pandemic - outside 10 Downing Street in London on 21 May 2020.

This was the day after an email, revealed by ITV News, invited Downing Street staff to "socially distanced drinks in the No 10 garden” on 20 May 2020.

The email was sent when lockdown restrictions were still in place, with people only allowed to meet one other person outside their household outdoors at the time.

It is understood that around 40 staff gathered in the garden that evening, eating picnic food and drinking, including the Prime Minister and his wife Carrie Johnson.

The Prime Minister has refused to say whether he attended the gathering, although it has been widely reported that both he and his wife were there.

The revelation has sparked anger from many, including key workers and family members of those who were unable to see ill or dying loved ones due to strict Covid restrictions in place.

Jon Richards, assistant general secretary of union Unison - which represents many NHS staff members - said workers “who were putting their lives on the line” to keep essential services running during the first Covid lockdown “will be dismayed and angered by these new revelations”.

He added: “No matter how exhausted and stressed, they weren’t allowed to socialise, let off steam or comfort their families.

“It’s inexcusable that those involved with setting the rules appear to have failed to follow them.”

The email was sent by Mr Johnson’s principal private secretary, Martin Reynolds, to over a hundred employees in Number 10, including the Prime Minister’s advisors, speechwriters and door staff.

In the email, Mr Reynolds - a senior No 10 civil servant who has run Boris Johnson’s private office since October 2019 - said: "Hi all, after what has been an incredibly busy period we thought it would be nice to make the most of the lovely weather and have some socially distanced drinks in the No10 garden this evening.

"Please join us from 6pm and bring your own booze!"

On the same day as the gathering, the Culture Secretary at the time, Oliver Dowden, gave the Downing Street coronavirus briefing, where he confirmed another 363 people in the UK had died with Covid in the previous 24 hours.

At the briefing, he told the public: "You can meet one person outside of your household in an outdoor, public place provided that you stay two metres apart."