What it could mean if ex-PM is found guilty

Boris Johnson has already been tried in the court of public opinion over Partygate, having given up the keys to No 10 when Conservative MPs and cabinet ministers mobilised en masse against him.

But the chance to rebuild his power base as a backbencher and chart a course back to Downing Street could suffer a serious setback when an inquiry into whether he misled parliament concludes.

What sanction could he face?

The seven-strong privileges committee of MPs, chaired by Labour’s Harriet Harman but with a Tory majority, will write a report with their definitive judgment about whether or not Johnson misled parliament. If they find against him, the group will decide if his action was intentional or reckless. Crucially, they would then recommend a sanction for Johnson to face.

A range of penalties can be recommended by the standards committee, made up of the same MPs but considering alleged breaches of Commons rules rather than parliamentary privileges.

These include a written apology, docking of salary or suspension from the Commons over a period.

What difference would the sanctions make?

Johnson has protested his innocence, so is likely to fight any penalty. But the sanction with the most serious implications would be a suspension from the Commons for 10 days or more.

That would automatically trigger a recall petition, allowing voters in his Uxbridge and South Ruislip constituency to cause a byelection if 10% of them call for one.

What happens after the committee makes a recommendation?

Any sanction along with the report on an MP’s misconduct has to be approved by the Commons as a whole. Traditionally, “house matters” are not whipped – meaning the government and opposition parties should not dictate to their MPs how to vote.

Johnson still has a loyal following among some in his party – having secured the backing of more than 100 MPs during the autumn Tory leadership race. But many fear that anything that plunges the Conservatives back into a standards row and reopens the wounds of the Owen Paterson debacle should be avoided at all costs.

What happens if a recall petition is triggered?

Johnson’s constituents will have six weeks to trigger a recall petition. If 10% of them did so, a byelection would be called; the ex-PM would still be able to contest the seat.