The referendum on PR was a bit of naughtiness from the Conservatives. It was part of the coalition agreement but they knew full well that it was a rubbish alternative to FPTP. I would prefer PR but there was no way I was supporting the offer in the referendum.
AV is not PR, but then it was never meant to be. It's a much fairer way to achieve majority government without diluting the 'party market' and making a mockery of the system. For the worst of FPTP just look at the 1983 election. AV would have eliminated tactical voting, and to some extent it would have given smaller parties more of a fighting chance.
PR may be fair but it is ineffective. And whilst the principle of democracy is that everyone gets a shout, no government is ever going to please everybody. Coalitions are a worthy idea, but too many are bad for the long-term.
The only naughtiness of the AV referendum was that the Tories resorted to negative (with a small n) tactics in their campaign. Dave and co point out the major deficiency of PR in general, of too many minor parties wielding power that doesn't reflect their standing. And before anyone mentions the lib dems in the latest government, consider the fact that they have fewer seats than their national vote would have merited under PR.