Labour’s Lisa Nandy has defended “Mr Rules” Sir Keir Starmer and said it was “not illegal to eat” after latest claims about alleged COVID rule breaking by the party leader.

Sir Keir has said he was working and stopped to eat when he was filmed having a beer in a room in Durham in April last year – at a time when the rules banned household mixing indoors apart from working.

Durham Police are now investigating the event and a leaked memo obtained by the Mail of Sunday appears to shed new light on what happened – but Ms Nandy accused the Tories of trying to “sling mud”.

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The Labour leader, who is a former Director of Public Prosecutions, is under pressure over the so-called beergate claims because he has himself been fiercely critical about Prime Minister Boris Johnson’s lockdown breach.

But Ms Nandy told Sky News’ Sophy Ridge on Sunday: “It is frankly absurd of the Tories to claim that this in any way equates to a prime minister who was under investigation by the police for 12 separate gatherings which included karaoke parties, bring your own bottle parties, pub quizzes, suitcases full of wine being smuggled through the back door.

“The prime minister lied about that, he denied that they happened, denied that he was there. He came clean and he laughed about it.”

Ms Nandy said that could not be equated with the Labour leader’s “work visit with planned breaks to eat”.

“It was not illegal to eat,” she said.

Ms Nandy declined to say whether Sir Keir should resign if he is found by police to have broken the rules.

She said to do so “lends legitimacy to something that is completely and utterly absurd”.

“I’m absolutely confident that no rules were broken, not least because this was investigated last time the Conservatives tried to sling mud at us and Keir Starmer was found to be completely in the clear,” she said.

“This is a guy who self-isolated six times during the pandemic.

“I don’t know a single other person who did that.

“He is Mr Rules, he does not break the rules.

“He was the Director of Public Prosecutions, not somebody who goes round tearing up rules when it suits him, in stark contrast to the prime minister.”

But Dominic Raab, the deputy prime minister, told Sky News: “It’s the rank double standards that drive people crazy.”

The comments came after the memo obtained by the Mail on Sunday indicated the dinner had been listed on the schedule for a day in April 2021 during the local election and Hartlepool by-election campaign.

The document stated that there would be a “dinner in Miners Hall” with City of Durham MP Mary Foy from 8.40pm to 10pm.

A note indicated a member of staff in Sir Keir’s office was to arrange a takeaway from the Spice Lounge.

The only business listed after the dinner was for Sir Keir to walk back to his hotel – he has previously claimed he “paused for food” and continued working after the meal, saying “the idea that nobody works at 10 o’clock at night is absurd”.

Ms Nandy told Sky News that the note “demonstrates exactly what went on was exactly what Keir Starmer has said went on”.

On Saturday, Diane Abbott became the first Labour MP to say publicly that Sir Keir may have to step down if he is fined over the incident.