I would prefer that our MPs are able to think fr themselves, change their minds, and change affiliation if they find their party no longer aligns with their values (Liberals who value environmental issues, anyone?). If the citizenry disagrees, well, that's what general elections are for.
The idea of our parliamentary system is that we vote for representatives, not parties, and certainly not for Prime Ministers. Whether that is borne out in reality is, of course, another issue. But punishing MPs for changing their alignment will just move us closer to a US-style whipped system.
