Several commenters in the previous post have taken issue with my assertion that Proportional Representation, and most especially the STV system, weakens the constituency link - and this is the reason why I cannot support it. Let me explain.
The proponents of STV deny that STV weakens the constituency link. In their view, if you have bigger constituencies with 10 or 12 MPs you still get the constituency link because seats are awarded proportionate to the votes received. Well, in the sense that you have constituencies and MPs who represent them, the constituency link still remains. Sort of.
The trouble is, that in 3, 6, 8, 10 or 12 member constituencies no one would really know who their MP is, just in the same way that no one now knows who their MEP is. The second effect is that when they eventually find out who their MPs are, which of them do they contact with a constituency issue? The probability is that they will contact the MP representing the party which they voted for. Nothing wrong with that, you may say, but I think it is a good thing that current MPs represent ALL their constituents, not just those who put a cross against them on the ballot paper.
Can we also dispel the myth that AV is in any way proportional. The Jenkins proposal of AV+ where you had additional members would be. But it would put a lot more power in the hands of the central party. And of course under STV, the party has even more power and influence over candidate selection.