[FridayoLeary]

While in theory you are correct the reality is somewhat different. Individual mps are beholden to their local party and would hesitate to vote on anything that may endanger their position. Backbenchers have brought down 3 successive governments. There also exists an upper chamber and a high court to appeal to. It's mostly a pretty stable system.

[toyg]

Individual MPs are not selected by local parties anymore, that ship sailed 30 years ago. Parachuting chums in safe seats it's been the accepted norm since (at least) Blair. Backbenchers do what they do because they're fighting among themselves, organized in gangs (sorry, "think-tanks" or "research groups") to bolster their own career opportunities.

There is no upper chamber that I know of (the Lords is legislatively dead, a strong government can simply ignore it), and the powers of the High Court, already diminished by recent reforms, are likely to be further curtailed very soon (read the tea leaves: the debate on "abusing judicial procedures to make law", once the remit of right-wing Americans, was the subject for an entire Reith Lecture cycle only a couple of years ago; after the Brexit saga, Tories will take an axe to the HC as soon as they can afford to do so).