For the Tory party leadership contests Tory MPs select two candidates for the membership to vote for.
The monarchy appoints the party leader of the major party to be PM.
The PM selects ministers.
The majority party forms the government, or failing a majority a coalition. That is democracy.
For the rank and file backbenchers of both parties to commandeer Parliament for their own nefarious purposes breaks both convention and democracy.

You can try and explain it away however you like but the process betrays democracy, the same as overturning the referendum results.
Bliar Blair should be charged with treason for conspiring with the EU against the clearly stated wishes of the UK majority.