The most reasonable thing to do for the leaving MPS is to stand down and trigger a by election, after all, they used the party to become MPs. However, they all realise that only rarely do independent candidates get elected in the UK. Most , if not all, would fall into that category. They are simply hanging onto the gravy train. If all of this leads to some sort of realignment in the political organisation of the nation, that may be no bad thing, since the present system is outdated and corrupted