By Lucy McDaid, ITV Westminster Producer
In Boris Johnson's 52-page Partygate dossier, the former prime minister accepts he misled MPs but claims his statements were made in "good faith" based on what he knew at the time.
Today his defence case has been released ahead of a grilling by the Commons Privileges Committee on Wednesday.
If found to have committed contempt of parliament, Mr Johnson could ultimately lose his seat and face the end of his political career.
Here are the key points from the document
Boris Johnson accepts he misled MPs
The former prime minister said he accepts he misled the Commons when he claimed that lockdown rules had been followed at gatherings in Number 10, but stresses his comments were made in "good faith" based on what he "honestly knew and believed" at the time.
He adds: "I did not intentionally or recklessly mislead the House on December 1 2021, December 8, 2021, or on any other date. I would never have dreamed of doing so."
'The inquiry is unfair and biased'
In the 52-page document, Mr Johnson questions both the "approach" and "the fairness" of the inquiry.
He says the cross-party group of MPs carrying out the investigation have not relied on any evidence from anonymous witnesses.
He says they "did not identify a single document which suggested that I was informed or warned by anyone…it fails to refer to the fact that a significant number of witnesses gave evidence that I had in fact received assurances that Rules were complied with”.
'There was no cover up'
The allegation that the former prime minister attempted to cover up rule-breaking in Downing Street is "illogical", Mr Johnson stresses.
In fact, he argues that "far from achieving a 'cover-up', I would have known that any deception on my part would lead to instant exposure".
He refers to pictures taken by the official Number 10 photographer, which he accuses of being "weaponised by the media".
He says it is "implausible" that pictures would have been taken if he had known the events were 'obviously' against the rules".
The Committee has already stated it's highly likely the former prime minister would have been aware there was rule-breaking taking place, which Mr Johnson rigorously denies.
'I might raise a glass to honour a colleague, but that was it'
Mr Johnson argues that Number 10 was a different workplace to most others during the pandemic.
"The nature and importance of the work meant that, unlike many other workplaces at the time, the building had considerable movement of people at regular intervals, and people were often at work very late into the night to keep the country running," he writes.
He says that, "No 10 went to great lengths to follow the guidance", but insists that while it was not always followed, no rules were ever broken.
When it comes to the gatherings, of which Mr Johnson confirms he attended five out of the six we know of, Mr Johnson says he was unaware any of those events "later escalated beyond what was lawful" once he had left.
On a garden party in May 2020 attended by at least 30-40 people, he "understood this to be a socially distanced outdoor meeting to boost staff morale and teamworking."
"In my view, an opportunity to thank staff and boost morale was essential for work purposes," he argues.
Defending his own attendance at the gatherings, he insists he never stayed "for more than half an hour, and sometimes far less."
"I was extremely busy," he said. "I might raise a glass to honour a colleague, but that was it."
He shouldn't have been given a Fixed Penalty Notice
Despite accepting the Metropolitan Police's conclusion that a birthday gathering for Mr Johnson on June 19, 2020, was unlawful, the former prime minister doesn't accept why him and the former chancellor Rishi Sunak, were given Fixed Penalty Notices for their attendance.
"We had a sandwich lunch together and they wished me Happy Birthday," he says.
"I was not told in advance that this would happen. No cake was eaten, and no-one even sang 'happy birthday'. The primary topic of conversation was the response to Covid-19."
Dominic Cummings gets a kicking
Mr Johnson's former, and now discredited, chief adviser Dominic Cummings, doesn't fare well in the mammoth defence dossier.
"It is no secret that Dominic Cummings bears an animus towards me," says Mr Johnson.
He argues to the committee that Mr Cummings "cannot be treated as a credible witness".
The Partygate: The Inside Story podcast brings you fresh revelations and our whistleblowers in their own words in the definitive behind-closed-doors story of how ITV News uncovered one of the biggest scandals of our era.