Today William Wragg MP made remarks in Parliament in which he undertook to vote in line with a three-line whip on a vote described as a confidence motion in the Government. The reason he gave – for voting such that he expresses confidence in the Government – was, by oblique reference, that he had submitted a letter of no confidence in the Prime Minister to the Chair of the 1922 Committee and wished for it to continue to carry weight in Conservative Party affairs, which it might not should he lose the right to sit as a Conservative by defying the whip.
The threat of losing party membership by defying a three-line whip seems to stem from the Prime Minister, who appoints and directs Government whips. But by announcing his submission of a letter, waiving the famous confidentiality this act enjoys by default, he has made an enemy of the Prime Minister in pretty much the same way as the way her whips are seeking to avoid by issuing a three-line whip – that is, making an expression of no confidence in her Government. Indeed, the Prime Minister now has a direct interest in seeing Wragg out of the Conservatives, as it would be one fewer letter against her in the 1922 Chair's in-tray.
Presumably, Wragg is no fool and there is a reason he knows he can declare his position without losing it instantly. But it's very difficult to find anything about how this actually works. When a Conservative Prime Minister decides Conservative MPs must vote a certain way or be ejected from the party, where does the authority for that decision come from, and why does it not also confer authority to eject for other reasons of disloyalty such as submitting a no-confidence letter?