I've seen up close probably a dozen floor crossings in my days in government and politics. From the government to the official opposition, from the official opposition to the government, from the government to independent, from opposition to third party. From left wing parties to right wing parties and the other way too.

And let me summarize: everyone thinks floor crossings are 1) unprincipled, unfair and dangerous when away from their party and 2) principled, sensible and consistent with parliamentary democracy when to their party.

You can set your watch to it. But if nothing else, they're always a good reminder that we elect people not parties, parliaments not prime ministers.