It's a somewhat jokey way to describe the unwritten UK constitution. Essentially, there are lots of traditions and norms and uncrossable lines and generally an understanding of how things are, and if any of the Good Chaps in government (they are all Good Chaps) find themselves (or are found to be) on the wrong side of those lines, then they do the right thing and resign, or at the top level, call for an election.Speaker Pelosi in the Dem caucus meeting, on Justice Thomas: "It's up to an individual justice to decide to recuse himself if his wife is participating in a coup." @NBCNews
— Kyle Griffin (@kylegriffin1) March 30, 2022
A bit like a university Honor System.
But what if they don't? Ah, well...