The British Labour party have accused Prime Minister Boris Johnson of having disregard for the "rules he puts in place for the rest of us" after a leaked email appeared to show his private secretary arranging a lockdown-busting drinks in the garden at No 10 Downing Street.

Martin Reynolds, the Prime Minister's principal private secretary, sent an email to more than a hundred Downing Street employees asking them to "bring your own booze" for an evening gathering, ITV has reported.

Mr Reynolds said they should "make the most of the lovely weather", despite England being under tough Covid-19 restrictions in May 2020.

Mr Johnson imposed England's first lockdown to combat Covid-19 in March 2020 and it was not until 1 June that groups of up to six people were allowed to meet outdoors.

The email from Mr Reynolds relates to an event said to have taken place on 20 May 2020.

Allegations of that gathering, said to have been attended by 40 people, emerged last week when Dominic Cummings, a former senior aide to Mr Johnson, said he had warned at the time the "socially-distanced drinks" would likely be against the rules and "should not happen".

The Sunday Times and ITV have alleged Mr Johnson attended the event with his wife Carrie Johnson.

Deputy Labour leader Angela Rayner said Sue Gray, the senior civil servant investigating allegations of lockdown-breaking gatherings in Government, should confirm the leaked email will form part of her probe.

The Cabinet Office official has already confirmed she is investigating the 20 May event as part of her inquiry, along with a separate 15 May 2020 garden gathering, which was revealed by a leaked photo showing the Prime Minister and staff sat around a table with cheese and wine.

Ms Rayner said: "Boris Johnson has consistently shown that he has no regard for the rules he puts in place for the rest of us.

"He is trying to get officials to take the fall for his own mistakes but he sets the tone for the way Downing Street and the rest of Government operates.

"At the time this party took place, key workers on the frontline were working round the clock to keep us all safe, people suffered loneliness and loss in unimaginably tough circumstances, and for the majority of the country our freedom was limited to a daily walk.

"Labour has welcomed Sue Gray's inquiry, but we need confirmation that this latest revelation, and any other parties not yet revealed by press investigations, will be covered by her probe."