How to topple a Tory leader

And now the European Research Group – that bonkers band of hard-line Brexiteers led by Jacob Rees-Mogg – is sharpening the knives.

At their most recent meeting they openly discussed how to oust the embattled prime minister.

But if it does get nasty, exactly how would they do it? What are the Conservatives rules?

How would it begin?

To trigger a no-confidence vote in the party leader, 15% of Tory MPs must write to the chairman of the backbench 1922 Committee, currently Sir Graham Brady. With 316 Conservative MPs in the House of Commons, Sir Graham must receive 48 letters to call a ballot.

How many MPs have sent letters so far?

It is not clear – but some have. Around 50 MPs discussed the ways of getting rid of the prime minister at a gathering of the European Research Group. A number of MPs told how they had already submitted letters of no confidence to Sir Graham and others discussed plans to follow suit.

What if they do pass the mark?

May would need the support of more than 50% of Conservative MPs – currently 159 – in the confidence vote to stay in office.

What would happen if she wins?

She can stay on as leader, however a narrow victory could seriously undermine her authority and may lead her to question whether it was right to carry on.

What if she loses?

If the PM lost the vote she would not be able to stand in the subsequent leadership contest arranged by Sir Graham.

What would the contest look like?

Candidates for the leadership must be nominated by two Conservative MPs. If only one candidate comes forward, he or she becomes leader. If a number of would-be leaders are nominated, the list is whittled down to a shortlist of two by MPs. The final two then go to a postal ballot of all party members, with the position of leader, and prime minister, going to the victor.

How long would all that take?

Sir Graham would be responsible for overseeing the contest and setting a timetable for the campaign, which would be expected to last around 12 weeks. May could remain in post during the campaign period.

Have we not been here before?

The double resignations of David Davis and Boris Johnson as Brexit secretary and foreign secretary respectively over the so-called Chequers plans sparked fevered speculation a leadership contest could be triggered in July. Such a challenge did not materialise and MPs disbanded for the summer recess. They returned to Westminster last week.

Who would be the runners and riders?

Boris Johnson, obviously. Jacob Rees-Mogg has built up a lot of support from the grassroots in recent months and might fancy his chances. Jeremy Hunt, Matt Hancock, Gavin Williamson and Dominic Raab would be in the frame from inside the cabinet. And what about Michael Gove? If it were the Gover up against Boris for the prize expect the fur to fly after their run-in when May got the top job.