Who do we know has written a no confidence letter? - BBC News
At least 48 letters have been sent to the chair of the 1922 Committee, triggering a vote.
One of the letters, from Steve Baker MP, sent to Sir Graham Brady

Theresa May will face a fight for her leadership after at least 48 members of her own party put in writing that they have lost confidence in her.

Any time the chair of the 1922 Committee of backbench Conservatives - Sir Graham Brady - receives letters from 15% of the party's MPs, a secret ballot is triggered.

If Mrs May wins, they cannot challenge her premiership for another year.

But, if she loses, there will be a leadership election and she will not be allowed to run. (You can see the process in the graphic below)

Here is a list of MPs who have publicly said they have submitted letters: