Mr Johnson sensationally resigned as a Conservative MP on Friday with immediate effect.

He furiously claimed a "witch-hunt" was under way to "take revenge for Brexit and ultimately to reverse the 2016 referendum result". Mr Johnson's 1,000-word statement attacked Rishi Sunak's government, and ultimately accused him of not being Conservative enough.

The Commons privileges committee's 14-month investigation, and its findings run to around a 30,000-word report - around the same length as the George Orwell novel Animal Farm.

Here, Sky News rounds up the key findings.

1. Boris Johnson deliberately misled the House over partygate

The Tory-majority committee found that Mr Johnson did mislead parliament over partygate on multiple occasions: twice in December 2021, once the next January and again in May 2022.

It asserted that Mr Johnson had "personal knowledge about gatherings which he should have disclosed".

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The report concluded that in "deliberately misleading the House", Mr Johnson had "committed a serious contempt" which was all the more serious because it was committed by the prime minister, the most senior member of the government".

The report said there is "no precedent" for a prime minister having been found to "have deliberately misled the House".

"He misled the House on an issue of the greatest importance to the House and to the public, and did so repeatedly," the cross-party committee concluded.

2. Committee 'unanimously' recommended a 90-day suspension

Had he not resigned as an MP, the committee would have recommended that Mr Johnson be suspended from the House for 90 days "for repeated contempt and for seeking to undermine the parliamentary process".

It found this was by:

• Deliberately misleading the House;
• Deliberately misleading the committee;
• Breaching confidence;
• Impugning the committee and thereby undermining the democratic process of the House;
• Being complicit in the campaign of abuse and attempted intimidation of the committee

The length of the proposed suspension is longer than was anticipated - but not the longest sanction we've seen.

3. Boris Johnson 'should not be entitled to a Member's pass'

Due to his resignation, the committee is unable to sanction Mr Johnson as it had hoped.

However, the report said: "In view of the fact that Mr Johnson is no longer a Member, we recommend that he should not be granted a former Member's pass" granting him access to the parliamentary estate.

4. Birthday party claims 'not convincing'

The committee report said it does "not regard as convincing" Mr Johnson's explanation that "it seemed to me… perfectly proper" for officials to be "asked to come and wish me a happy birthday".

This relates to a gathering that took place on 19 June 2020, at the height of lockdown.

The report continues that Mr Johnson was unable to explain why he considered his wife and interior designer "absolutely necessary participants" in a work-related meeting.

"His assertion that the prime minister's family are entitled to use every part of the building does not constitute an explanation," it said.

Mr Johnson was fined for attending the gathering in the Cabinet Room in Downing Street.

5. Gatherings at Number 10 and Chequers

The report revealed that on 18 May, the government provided the committee with "new evidence relating to 16 gatherings at Number 10 and Chequers" without any prior notice. Chequers is the official country residence of British prime ministers.

An accompanying statement from the government had said: "As part of their work preparing Boris Johnson's witness statement for the COVID Inquiry (due to be filed on 29 May), the counsel team supporting Mr Johnson identified a number of diary entries as potentially problematic.

"These entries […] are based on an assessment by Government Legal Department as to events/activities which could reasonably be considered to constitute breaches of COVID Regulations."

The committee said this was disclosed to Mr Johnson the next day.

6. 'Wine time Fridays'

According to one junior official who gave evidence to the committee, press officers would gather in Downing Street for "wine time Fridays" from 4pm, where social distancing was "not enforced".

"Number 10, despite setting the rules to the country, was slow to enforce any rules in the building," the official testified.

"The press office wine time Fridays continued throughout, social distancing was not enforced and mask wearing was not enforced."

The official said they enquired whether masks should be worn and was told the "science advice was that there was 'no point' and had 'very little effect on the spread on COVID'".

"This was all part of a wider culture of not adhering to any rules. Number 10 was like an island oasis of normality.

"Operational notes were sent out from the security team to be mindful of the cameras outside the door, not to go out in groups and to social distance, it was all a pantomime.

"Birthday parties, leaving parties and end of week gatherings all continued as normal. Those responsible for the leadership of Number 10 failed to keep it a safe space and should have set rules from the start that these gatherings should not continue.

"It was only more than a year into the pandemic that Number 10 set up a one way system and desk divider screens."

7. Kangaroo courts and witch-hunts

Committee members condemned Mr Johnson for distancing himself from language like "kangaroo courts" and "witch-hunts" while giving evidence to the committee, but then using that same "abusive" language himself in his statement last week.

It said: "This leaves us in no doubt that he was insincere in his attempts to distance himself from the campaign of abuse and intimidation of committee members.

"This in our view constitutes a further significant contempt."