Sue Gray’s inquiry into allegations of lockdown-breaching parties at the heart of Government may have been seriously hindered by the police investigation.

But her update into the Cabinet Office investigation published on Monday still contains some damning verdicts and explosive revelations.

– Police investigating at least 12 events

Ms Gray looked into 16 separate gatherings across Downing Street and wider Government between May 15 2020 and April 16 last year.

Of those, her report sets out that the Metropolitan Police are now investigating all but four of those events.

Scotland Yard said it was investigating allegations spanning eight dates, but did not set out how many specific allegations they were looking at.

– Gatherings include PM’s birthday and event in official flat

The dozen events being looked at by officers include a “gathering in the No 10 Downing Street flat” on November 13 2020, the night Mr Johnson’s former aides Dominic Cummings and Lee Cain left their roles during a bitter power struggle.

Police were also investigating the June 19 2020 event in the Cabinet Room at No 10 to mark the Prime Minister’s 56th birthday.

Two other Downing Street gatherings that officers are inspecting took place on April 16 last year, on the eve of the Duke of Edinburgh’s funeral, when the Queen was pictured mourning alone.

– Gray held back much of what she learned

Ms Gray conceded it was “not possible at present to provide a meaningful report” about the “extensive factual information” she has unearthed about the events under police investigation while officers were continuing their work.

She decided against publishing “factual accounts” about the remaining four events, saying: “I do not feel that I am able to do so without detriment to the overall balance of the findings.”

Downing Street caved to pressure to concede it would ask Ms Gray to publish a fresh assessment after the police investigation concludes.

– Failures of leadership and too much drinking

Despite that, Ms Gray was able to conclude: “At least some of the gatherings in question represent a serious failure to observe not just the high standards expected of those working at the heart of Government but also of the standards expected of the entire British population at the time.”

She criticised “failures of leadership and judgment” in No 10 and the Cabinet Office.

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

Ms Gray, who was for a time a pub landlady, called for a robust policy to cover drinking in Government, saying that the “excessive consumption of alcohol is not appropriate”.

– Pity for the ‘fall guy’

One staff member believed to have been lined up for the chop to appease public anger is Martin Reynolds, the Prime Minister’s principal private secretary sent the email inviting staff to the “bring your own booze” event in the first lockdown.

But Ms Gray has made that sacking a little bit harder by noting that with swelling staff size in No 10 the leadership structures “fragmented and complicated and this has sometimes led to the blurring of lines of accountability”.

“Too much responsibility and expectation is placed on the senior official whose principal function is the direct support of the Prime Minister. This should be addressed as a matter of priority,” Ms Gray wrote.