How successor will be chosen

■ If Mrs May’s deal goes through, the UK is likely to leave the EU on May 22 and she would resign as Tory leader that day but stay on as interim PM while the contest to replace her begins.

■ Any Tory MP can stand but they need two nominations from colleagues.

■ A series of secret votes would be held every Tuesday and Thursday among the 314 members of the Conservative Parliamentary Party.

■ The last-placed candidate is eliminated at every stage and once it is clear who the front-runners are the backmarkers usually drop out and support someone else.

■ After David Cameron stood down following the referendum in 2016 there were five candidates in the first round, who were whittled down to two: Theresa May and Andrea Leadsom.

■ The final two candidates then move on to the second phase, when party members vote by postal ballot.

■ Candidates will be expected to make speeches to members and tour the country to try to win support. This second phase is likely to last for up to a month.

■ Only members who have been in the party for three months or more can vote in a leadership contest, so joining now would not entitle you to a say.

■ Conservative sources say the whole process could be completed within a month to six weeks.