Boris Johnson is reportedly looking for ways to appease possible Conservative rebels as the partygate affair threatened to reignite over new rule-breaking claims.
Allegations have surfaced that senior civil servant Sue Gray was told about a potential gathering in the Downing Street flat on the evening of the Prime Minister 's 56th birthday during her inquiry into No 10 and Whitehall Covid lockdown parties but opted not to investigate.
The Cabinet Office said it seriously disputes the version of events as detailed in The Sunday Times but Labour is demanding answers over whether a rule-breach occurred.
It comes as the BBC reports the number of Tory MPs who have submitted their letters of no-confidence could be in the 40s.
One MP was asked how many colleagues they think had called for the PM to quit. They replied: "My hunch is it's in the high 40s."
More Tories in recent days have publicly announced they want a confidence vote in the future of Johnson's leadership in response to his handling of the revelations about No 10 lockdown parties.
The number to have confirmed they have submitted a letter of no confidence has almost reached half the amount needed to trigger a vote, although the actual figure could be higher given MPs do not have to declare if they have handed in a letter.
Sir Graham Brady, chairman of the 1922 Committee of backbenchers, will be obliged to order a confidence vote if 54 Tory MPs demand one.
Speculation about the Prime Minister's future comes after questions were raised about the independence of Gray's final report, with claims that she was lobbied not to name officials who attended events while England was in lockdown.
The Sunday Times reported that the Prime Minister's chief-of-staff Steve Barclay edited out details about a gathering in the Johnsons' Downing Street residence on November 13 2020, removing details about music being played at a so-called "Abba party" following the departure of controversial aide Dominic Cummings.
Separately, The Daily Telegraph said Gray was told by at least four officials about Abba songs being played on the night in question, but her report published last week did not make mention of music being heard.
The Cabinet Office was forced to deny that the head of the Civil Service, Simon Case, had requested for his name to be removed from the report.
The department said it was not correct that Mr Barclay edited or influenced the findings, with a spokesman adding that, while it was true the team took representations from those who were criticised in the report, such a practice was part of a "usual process in such matters".
Officials also said it was not true that Gray had declined to look into claims of a second gathering on the night of Mr Johnson's birthday in June 2020 - alleged to have taken place only hours after the surprise Cabinet room bash which saw him fined for breaching coronavirus rules.
The Sunday Times reported that an unnamed aide claimed to have told Gray's investigation in January that they had messages showing Mrs Johnson met with "several" male friends that evening, with the Prime Minister later heading up to the flat where they were gathered.
The paper said the aide, who has since reportedly written to the Cabinet Secretary about the messages, told Ms Gray's team they did not want to forward the messages to them but were prepared to show investigators in person.
But the Cabinet Office said the informant had not been willing to provide the messages or to meet in person, so their email exchange was forwarded to the police once the Operation Hillman inquiry started.
The police did not investigate the alleged evening flat gathering and by the time the aide offered to share the messages with Ms Gray, the Cabinet Office said the probe had been wrapped-up.
Deputy Labour leader Angela Rayner has followed-up the allegations by writing to Case to call on him to release any correspondence that relates to Johnson's "whereabouts" that evening.
She said: "It is crucial that you now advise the Prime Minister to come clean about his involvement in this apparently rule-breaking gathering."
When Parliament returns next week from its recess to mark the jubilee, the Commons Privileges Committee is likely to soon commence its investigation into whether the Prime Minister misled MPs with his reassurances that Covid laws were followed in No 10.
Rayner said the committee should be handed any information related to the possible evening birthday gathering as part of its inquiry.
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