Sue Gray, the senior civil servant tasked with investigating events at Downing Street and other government departments, is widely expected to deliver her report to the prime minister later this week.
According to reports, Dominic Cummings, the former chief adviser to Mr Johnson at No 10, who has claimed his former boss “lied” to parliament over the events, will also be interviewed by Ms Gray on Monday as part of her inquiries.
Police officers guarding No 10 at the time of alleged rule-breaking parties have reportedly already been spoken to for the probe.
Asked how significant their information was, a source told The Telegraph: “Put it this way, if Boris Johnson is still prime minister by the end of the week, I’d be very surprised.”
Some Conservative MPs have already called on the prime minister to resign over the scandal, including former ministers Caroline Nokes and David Davis, and others have sent no confidence letters to the chairman of the 1922 Committee, Sir Graham Brady.
Aaron Bell, the Tory MP for Newcastle-under-Lyme, became the latest backbencher to submit a letter at the weekend, according to The Sunday Times. A total of 54 MPs are required to do so if a no confidence vote is to be triggered.
But many are reserving judgement on the prime minister’s future at No 10 until Ms Gray’s findings on multiple events held during Covid restrictions, including the “bring your own booze” gathering on 20 May 2020, are published.
Asked whether Mr Johnson’s political future hung in the balance over the report, the senior Tory MP Steve Baker told The Independent on Friday: “I don’t see how anyone can objectively say otherwise.”
Speaking on Sunday, Dominic Raab, the deputy prime minister, claimed there had been a “rallying” around Mr Johnson after the dramatic defection of the Bury South MP Christian Wakeford to Sir Keir Starmer’s Labour Party.
However, he dodged questions over whether the report would be published in full, telling the BBC that the “process will be for the prime minister to decide”, and claimed he was “not quite sure the shape and form it would come”.
“The substance of the findings will be – there will be full transparency,” he added. “Indeed, he [Mr Johnson] has said he’ll come back to the House of Commons and make a statement, so there’ll be full scrutiny.”
However, on Saturday, Angela Rayner, Labour’s deputy leader, stressed: “The Sue Gray report must be published in its entirety with all accompanying evidence”.
She added that the prime minister “cannot be allowed to cover up or obscure any of the truth when he has insisted on a hugely protracted internal probe to tell him which parties he attended and what happened in his own home”.
Ms Gray’s inquiry has also reportedly been widened to examine socialising at the prime minister’s flat above No 11 Downing Street, involving government advisers and close friends of the prime minister’s wife, Carrie.
The Cabinet Office declined to comment at the weekend, but Mr Cummings has previously claimed there was a “party” at the flat on 13 November 2020 – the same day he left his government post – while England faced its second lockdown.
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