Is PR really such a fair system?

It's easy to see why the Tories are so opposed to the idea of proportional representation - just look at the maths. Even in this last election, where Labour did pretty abysmally, and the LibDems only averagely, between them they commanded more than 50% of the votes cast, and thus under PR could have formed a majority coalition. And this is what almost inevitably would have happened - the LibDems are naturally ideologically aligned with Labour. And so it would be for the foreseeable future - a series of Lib-Lab coalitions with the Tories in permanent opposition. Of course this assumes that the parties would stay as they are, and that the electorate would continue to vote as they now do - but you can see why it has no attraction for the Conservatives.