Brexiteers have attempted a coup against Theresa May (pictured in Downing Street tonight) in fury at her draft deal with the EU - but they will have to navigate Tory rules to force her out

Brexiteers have attempted a coup against Theresa May in fury at her draft deal with the EU - but they will have to navigate Tory rules to force her out.

The Prime Minister insisted she plans to 'see this through' to make clear to the rebels she will not quit voluntarily.

This is how the Tory Party rules work:

What is the mechanism for removing the Tory leader? Tory Party rules allow the MPs to force a vote of no confidence in their leader.

How is that triggered? A vote is in the hands of the chairman of the Tory Party's backbench 1922 Committee, Sir Graham Brady.

A vote of no confidence must be held if 15 per cent of Tory MPs write to the chairman. Currently that threshold is 48 MPs.

Letters are confidential unless the MP sending it makes it public. This means only Sir Graham knows how many letters there are.

This possible delay could give Mrs May a 'grace period' where she knows a contest is imminent but not yet public knowledge.

How is a vote announced? There are few fixed rules but Sir Graham is likely to inform Downing Street or the Chief Whip and then make a public announcement.

Sir Graham is likely to check with the MPs who have sent him a letter before making an announcement in case any of them want to withdraw. This will happen secretly.

How will the vote happen? After it is announced, a vote will happen quickly, with Tory MPs invited to cast a secret ballot in a Commons committee room.

Voting will be open for one day and Sir Graham will announce the result at the end.

What needs to happen for Theresa May to win? Officially, Mrs May only needs to win a simple majority of Tory MPs - currently that is 158 MPs.

Politically, winning by one would be devastating. If more than 100 MPs vote against her, most observers think she would be finished.

A vote is in the hands of the chairman of the Tory Party's backbench 1922 Committee, Sir Graham Brady (file image)

What happens if she loses? Mrs May is sacked as Tory leader and Sir Graham will announce a leadership contest. She cannot stand in the contest.

She will probably stay on as Prime Minister until a replacement is elected but have no political power or authority to do anything.

What happens next? In a Tory leadership contest, any MP can stand with a proposer and seconder.

Tory MPs vote several times a week on the candidates with the last place candidate being removed from the race at each ballot.

When there are only two candidates remaining, a run off is held among all Tory members in the country.

How long will it take? The first phase depends on how many candidates there are. A large field could mean a fortnight or more of regular ballots.

In the past, the second round has taken anywhere from four to 12 twelve weeks - but some thing a vote of Tory members could be finished in just a week.