Sue Gray’s report into the Partygate scandal attacks “a serious failure” to abide by the “standards expected of the entire British population” during the Covid pandemic.

       The long-awaited inquiry into the No 10 parties concludes “too little thought” was given in Boris Johnson’s No 10 into “the risks they presented to public health and how they might appear to the public”.

       “There were failures of leadership and judgment by different parts of No 10 and the Cabinet Office at different times,” Ms Gray writes.

       “Some of the events should not have been allowed to take place. Other events should not have been allowed to develop as they did.”

       The senior Whitehall mandarin highlights how junior staff “believed that their involvement in some of these events was permitted given the attendance of senior leaders.

       Recommended What Sue Gray said about each Downing Street party Sue Gray halted probe into event with ‘food and alcohol’ in Downing Street flat Sue Gray report reveals partygoer vomited and scuffle broke out at No 10 leaving do

       “The events that I investigated were attended by leaders in government,” the report states, adding: “The senior leadership at the centre, both political and official, must bear responsibility for this culture.”

       Ms Gray also criticises the revelation that, on at least one occasion, a security guard protested at a party taking place, but his warning was dismissed.

       “Some staff had witnessed or been subjected to behaviours at work which they had felt concerned about but at times felt unable to raise properly,” she writes.

       “I was made aware of multiple examples of a lack of respect and poor treatment of security and cleaning staff. This was unacceptable.”

       Ms Gray also concludes that the public will be “dismayed that behaviour of this kind took place on this scale at the heart of government”.

       The publication of the report is expected to trigger more demands from appalled Tory MPs for a no-confidence vote in his leadership – with 54 signatures needed to trigger the contest.

       However, she adds: “It is my firm belief, however, that these events did not reflect the prevailing culture in government and the Civil Service at the time.”

       Most said they were awaiting Ms Gray’s conclusions before deciding whether to act, although much of the anger of earlier in the year has cooled as the saga has dragged on.

       The prime minister will make a statement to MPs later, when he will repeat his claim that he did not realise he and others were breaking the rules at the time, so did not lie to parliament.

       Recommended Sue Gray report: Partygoer left No 10 at 4.20am on eve of Prince Philip’s funeral Sue Gray report: Read the document and see the photos in full What was missing from Sue Gray’s ‘update’ on the Partygate scandal?

       He is expected to tell the Commons: “I commissioned this report to set the record straight and allow us all to move on. I accept full responsibility for my failings. I am humbled by the whole experience. We have learned our lesson.”

       The phrasing will be seen as an argument that Mr Johnson has already put right the failings that led to the law-breaking, with his shake-up of No 10 earlier this year.