Boris Johnson’s political fate is in the hands of the Privileges Committee as the panel of MPs decides whether he lied to Parliament over partygate.

Before his highly anticipated appearance before the panel, a 110-page bundle of evidence has been released.

– What have we learned?

The latest documents indicate that Boris Johnson was warned against claiming that all coronavirus guidance had been followed at No 10 but went ahead and issued a denial anyway.

Martin Reynolds, who was Mr Johnson’s principal private secretary, questioned whether the suggestion was realistic and claimed he (Mr Johnson) agreed to delete the mention of guidance before going on to make the denial at Prime Minister’s Questions on December 8, 2021 regardless.

Cabinet Secretary Simon Case told the inquiry he did not give Mr Johnson assurances that the guidance was always followed.

Mr Case also said he did not advise that no parties were held in Downing Street, and was not aware of others telling the then-prime minister that.

Jack Doyle, who was Mr Johnson’s communications chief when the partygate story broke, said he “believed no rules were broken”.

But asked whether he told Mr Johnson “Covid guidance” was followed at all times, Mr Doyle said: “No.”

– What did Mr Johnson say?

Mr Johnson told MPs on December 1 that “all guidance was followed completely in No 10” and on December 8 that “the guidance was followed and the rules were followed at all times”.

In his written evidence he said that on December 1 he meant to repeat the line that had already been given to the press that “Covid rules were followed at all times” but it was his “honest and reasonable belief” that all guidance was followed too.

But he accepted that it “did mislead the House”, although at the time it was “the truth as far as I knew it”.

By December 8, Mr Johnson said he still “honestly and reasonably believed” the rules and guidance had been followed.

– Are there any other revelations in the published evidence?

Mr Reynolds said the wording of an email he sent inviting No 10 staff to “socially distanced drinks” at a “bring your own booze” event in the Downing Street garden was “totally inappropriate”.

The senior official said he had not drafted the invitation to the May 20, 2020 event but he did sign off on it.

“With the benefit of hindsight, the language used was totally inappropriate and gave a misleading impression of the nature of the event,” he said, stressing it “was not a party in any normal sense of the word”.

– What is the Privileges Committee?

It is a Commons committee that has been charged by MPs with undertaking the parliamentary investigation into whether Mr Johnson lied over the partygate row.

The committee, a seven-member cross-party body with a Labour chair but a Tory majority, is examining evidence from at least four occasions when Mr Johnson may have misled MPs with his assurances to the Commons that lockdown rules were followed.

The committee will publish its findings on whether Mr Johnson committed a contempt of Parliament and can make a recommendation on any punishment. But the ultimate decision will lie with the full House of Commons.

– Who is the chair?

Labour grandee Harriet Harman is chair of the Privileges Committee. In Parliament since 1982, she is the longest-standing female MP and a former Cabinet minister.

– What about other members?

Other members are Tories Sir Bernard Jenkin, Sir Charles Walker, Andy Carter and Alberto Costa, Labour’s Yvonne Fovargue and the SNP’s Allan Dorans.

– What will Boris Johnson be asked when he appears for his Wednesday afternoon showdown?

The committee has been clear that the purpose of the inquiry is to consider whether Mr Johnson misled Parliament, rather than comb over the various details of the partygate furore.

The committee has said: “The evidence strongly suggests that breaches of guidance would have been obvious to Mr Johnson at the time he was at the gatherings.”

– What will his defence be?

Mr Johnson has always protested his innocence, rejecting any suggestion that he “knowingly or recklessly misled Parliament”.

He set out his core defence in a 52-page dossier, in which he stressed that he trusted the assurances of key aides and said that “hindsight is a wonderful thing”.

It is a defence that refers to the “cramped” workplace of No 10 as well as his own belief that no guidance or rules were being breached at any gathering.

Mr Johnson placed great stock in both the assurances he had received as prime minister and the fact that no-one around had expressed concerns themselves, while also making much of the fact that there is no evidence that he ever received warnings about breaches of guidance.

Elsewhere, he also takes issue with the remit and fairness of the committee process.

– What is the position of the Government?

Prime Minister Rishi Sunak, who is not planning on watching proceedings, has said he will not seek to influence MPs on the committee.

He is expected to grant a free vote in the Commons on any sanction that may be recommended.

But if Mr Johnson is found in contempt and sanctions are recommended, this is likely to cause a headache for the current Prime Minister.

What could the sanctions be?

If the committee finds a contempt has been committed, it will recommend a punishment which would then have to be approved by the House of Commons as a whole.

Sanctions could range from a simple apology to ordering that Mr Johnson be suspended from Parliament.

Could Mr Johnson be forced out of Parliament?

Any suspension of 10 sitting days or more could trigger a tricky recall by-election in his Uxbridge and South Ruislip seat.

If 10% of eligible registered voters in the constituency sign a recall petition then a by-election will be called.

Mr Johnson would be eligible to stand again, but in 2019 he had a majority of 7,210 over Labour and the Opposition would be keen to claim a high-profile scalp.