Police are now in contact with the Cabinet Office over claims the Prime Minister’s aide organised a “bring your own booze” gathering in the Downing Street Garden during the first lockdown.

The Metropolitan Police has confirmed it is in contact with the Whitehall department following political calls to investigate the allegations.

Martin Reynolds, the Prime Minister’s principal private secretary, sent an email to more than 100 Downing Street employees asking them to “bring your own booze” for an evening gathering, ITV reported.

Mr Reynolds said they should “make the most of the lovely weather”. This occurred when England was under tough coronavirus restrictions.

When the message was sent, groups were not allowed to meet socially outdoors.

A spokesman for Scotland Yard said: “The Metropolitan Police Service is aware of widespread reporting relating to alleged breaches of the Health Protection Regulations at Downing Street on May 20 2020 and is in contact with the Cabinet Office.”

Multiple reports have suggested the Prime Minister attended the event with his wife, Carrie Johnson.

Daily Echo: Boris and Carrie Johnson (PA)Boris and Carrie Johnson (PA)

The Prime Minister avoided questions on Monday about whether he attended the evening gathering.

The Liberal Democrats said if rules were found to be broken then “those responsible should face the full force of the law”.

The party’s home affairs spokesperson Alistair Carmichael said: “This garden party looks like a clear breach of lockdown rules at a time the public were being ordered to stay at home.

“Boris Johnson himself said just days after this party that the police should step in to stop people holding outdoor gatherings.

“It would absolutely reek of double standards if the police don’t investigate these allegations in full.”

The Metropolitan police had tweeted on the day the alleged “bring your own booze” event is said to have taken place, telling people they could have a picnic, exercise or do sport outside providing you are “on your own, with people you live with, or just you and one other person”.

That day the then culture secretary Oliver Dowden said in a Downing Street press conference that people could meet with one person from another household while outdoors and with two-meter social distance in-between.

No. 10 said it would not be commenting on the allegations while Sue Gray, a senior civil servant, carries out her inquiry into numerous allegations of rule-breaking events being held in Downing Street during the coronavirus pandemic.

Downing Street denied reports that Mr Reynolds is to be moved to another post following the claims.

The Prime Minister’s official spokesman said he was staying in his current role.