Boris Johnson is being grilled by the Privileges Committee on Wednesday as he aims to defend himself against claims he lied to Parliament over the partygate scandal.
Here is what you need to know about the highly anticipated session.
What is the Privileges Committee?
It is a Commons committee that has been charged with undertaking a parliamentary investigation into whether Mr Johnson lied to MPs over the partygate row.
This is not the first time that MPs have considered whether an individual is in contempt of Parliament, but it is perhaps one of the most high-profile cases.
The committee, a seven-member cross-party body, 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.
Ms Harman, due to stand down at the next general election, has long been an outspoken advocate for equality in politics and a strong feminist. She has served in numerous government roles and senior positions in Labour under a succession of leaders, and also served as deputy leader.
What about other members?
Sir Bernard Jenkin is another veteran MP. A Conservative, he has been in Parliament since 1992.
A veteran Tory Eurosceptic and chairman of the powerful Liaison Committee, he was a critic of Mr Johnson’s handling of the Chris Pincher affair and is an often vocal voice from the backbenches.
Sir Charles Walker, another member of the committee, is standing down at the next election. Another independently minded Conservative backbencher, he made headlines last year for his emotional criticism of the chaos that engulfed the final days of the Truss administration.
Conservative MP Andy Carter, who was elected in 2019 to represent Warrington South, is another member of the committee.
Alberto Costa, elected in 2015 for South Leicestershire, is the final Tory member of the committee.
Labour’s Yvonne Fovargue, an MP since 2010, has held a number of shadow ministerial roles during her time in Parliament. She has been a member of the committee since September 2021.
Allan Dorans is the sole SNP member. An MP since 2019, he represents Ayr, Carrick and Cumnock.
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.
Mr Johnson retains support within both the Conservative Party and within Mr Sunak’s Cabinet.
Northern Ireland Secretary Chris Heaton-Harris raised eyebrows earlier this month when he offered a staunch defence of Mr Johnson when asked about the probe, while Home Secretary Suella Braverman said over the weekend that she admired the former prime minister.
Who is Mr Johnson’s barrister?
Lord Pannick KC, one of the most widely-respected barristers in the UK, is in Mr Johnson’s corner for the encounter with the Privileges Committee.
No stranger to high-profile cases, he led the Article 50 cases against the Government at the Supreme Court in the wake of the Brexit vote.
He has led Mr Johnson’s bid to prove he did not “intentionally or recklessly” mislead MPs.
