I'm not sure how many constituencies will actually end up with a different candidate using AV rather than FPTP. I would suggest that in most it will make little difference based on current voting patterns. However, in marginal seats it would be likely to result in a much closer election and a fairer contest when the vote is split three or four way.

It would result in many more 'marginal' constituencies, which means that more people would actually influence the result of the election than at present. Since I have been old enough to vote Lewisham West (& Penge) has never really been regarded as a marginal. My vote could not influence the party(s) that form the government or even have much impact on the MP. On the other hand, if we lived in Hampstead, where three parties were all around 32%, a vote for any of these large parties can make a big difference. AV does not do away with this problem, but it does start to address the problem.

With a number of smaller parties; Lib Dem, UKIP, Greens, it is less likely that a single party will always control who forms the government if we have more coalitions. But then I see the third party in coalition as a balance against the worst excesses of a single party in power.

Once we have a slightly more democratic system for the commons, the Lords can be moved to a fully proportional system (at least for the majority of members).

We have been experimenting with different voting methods since 1997 for local assemblies and directly elected mayors. Now we have the chance to learn from these successes and use a better system for Westminster. Unfortunately I fear that those who want to punish Clegg and those who benefit from the status quo will join together to kill off any chance of electoral reform for another 50 years.