Could the Lib Dem marginal meltdown mean the Tories gain from A.V.?

By Lord Ashcroft

A referendum on the Alternative Vote is currently planned for 5 May 2011. The pollsters have turned their attention to the likely ramifications should the public decide to adopt such a system for general elections. There has been a widespread assumption that the Conservatives have nothing to gain from electoral reform, and the work that has been done so far – such as the YouGov poll for the Spectator earlier this month – has indeed suggested that the Tories would be the biggest net losers when comparing A.V. with First Past The Post (FPTP). As ever, though, national polls can only tell us so much – it would be in the marginal seats that A.V. would make a decisive difference.  Would voters in these seats behave differently under the two systems? And would the effect be different depending which parties were in contention?