A Downing Street chief boasted they had "got away with" partygate rulebreaking, Sue Gray's report has revealed, as she blamed senior leaders for failing to follow Covid rules.

       A months-long inquiry by the civil servant concluded that "whatever the initial intent, what took place at many of these gatherings and the way in which they developed was not in line with Covid guidance at the time".

       Ms Gray, the former head of propriety and ethics in the Cabinet Office, investigated 16 events in Whitehall during the pandemic, including a karaoke party where one staff member was so drunk they were sick and two others had a fight.

       Her report places the blame at the feet of senior leaders in Downing Street, including politicians and civil servants.

       "Many of these events should not have been allowed to happen," she said.

       "It is also the case that some of the more junior civil servants believed that their involvement in some of these events was permitted, given the attendance of senior leaders.

       "The senior leadership at the centre, both political and official, must bear responsibility for this culture."

       'We got away with it'

       One message revealed in her report shows that Martin Reynolds, Mr Johnson's principal private secretary, boasted that staff had "got away with" breaking the rules.

       In a fragment of a message to a special adviser, he said: "Best of luck - a complete non-story but better than them focusing on our drinks (which we seem to have got away with)."

       He was referring to the "BYOB" garden party on May 20, 2020, which took place during the first lockdown.

       The report runs to 60 pages and contains nine photos of gatherings in Downing Street during the pandemic, including images of Mr Johnson and Rishi Sunak at the Prime Minister's birthday party in June 2020.

       The photograph of Mr Johnson shows him and Simon Case, the Cabinet Secretary, around the Cabinet table. Mr Johnson is holding aloft a can of beer.

       The Gray report reveals further detail about some of the parties in No 10, including the fact that one attendee left Downing Street as late as 4.20am on the night that staff partied on the eve of Prince Philip's funeral.

       The report also appears to reveal that staff members thought their behaviour was inappropriate at the time. Several messages between staff in the report name Mr Reynolds as being involved in organising the events.

       In one email about a staff member's leaving party, one No10 employee wrote: "Hi Martin and Stuart [Glassborow] would like to do speeches tomorrow, when we have our drinks which aren't drinks. What time are we planning on the drinks?"

       In a WhatsApp exchange between Lee Cain, Mr Johnson's former Director of Communications, and Mr Reynolds, Mr Cain said staff could not host "some sort of party" for a departing member of staff.

       "So you're saying nothing for [the official]," Mr Reynolds replied.

       Mr Cain said: "I think it's your decision my friend, not mine! But it obviously comes with rather substantial comms risks."

       Ms Gray's report reveals that at the event, a staff member was sick and a fight took place.

       "The event lasted for a number of hours," she said.

       "There was excessive alcohol consumption by some individuals. One individual was sick. There was a minor altercation between two other individuals."

       The morning after another drinks event in the Downing Street garden on May 20, 2020, a special adviser emailed Mr Reynolds thanking him for supplying alcohol.

       "Thank you so much for organising these drinks and for providing the wine," the email said. "A very kind thing to do and I know everyone really appreciated it."

       'End of year meeting with wine and cheese evening'

       Another event organised by a different member of staff had its name changed from "wine and cheese evening" to "end of year meeting with wine and cheese".

       For other events, including a leaving party for Kate Josephs, the head of the Covid taskforce, emails show that staff were asked not to come into the office if they had not already planned to, and mention the need to remain "Covid secure" or follow "hands, face, space" guidance.

       Ms Gray said she had "broadly" followed the convention that only senior civil servants are ever named in public documents, but given "unique circumstances" had decided only to name senior staff and special advisers who are "significant to the organisation of such gatherings".

       Her conclusions are likely to prompt further questions for Conservative MPs over whether Mr Johnson is the right man to lead the country. At least three new letters of no confidence have been submitted since the May local elections.

       The publication of the report means that a Commons investigation into whether Mr Johnson deliberately misled Parliament can now begin - although The Telegraph understands it is unlikely to kick off for at least a fortnight.