I agree with everything M0nica and Jane10 have said. This is the UK, not the US, and in this country we vote for the candidate, not the party.
And consider this: we are on the brink of something interesting with these 11 breakaway MPs (we certainly live in interesting times). If they were all to stand in a by-election, I would hope they would all be re-elected under their new independent status. But just supposing they weren't. We would immediately lose the impetus in Parliament of the principles they are standing up for. Everything they are trying to do would be swept away. We need to allow them to continue to have their voice in Parliament, to challenge all that is wrong in their original parties.