The otherwise excellent Peter Kellner shows sympathy for the Conservatives ‘ dislike of PR and trots out the old shibboleth of those who have no practical experience of it.
The principled reason is that (first-past-the- post) keeps the constituency link. Each MP represents a relatively small population of fewer than 100,000. Any proportional system would gravely weaken that link.
In both parts of Ireland and particularly in NI where both systems operate, we know all to well that the constituency link is as strong as ever. True. in multi-member constituencies the link is shared; but that doesn’t mean it’s weakened. Indeed if anything it’s stronger, because elected reps compete with members of their own party as well as their opponents. Nothing like competition to improve the service! A list system as under AV+ as in Scotland may be said to weaken it, but no way PR STV.
If an expert like Kellner can repeat the hoary old line, it augurs badly for a successful outcome of Lib Dem attempts to persuade the Tories.