Giving second preferences to the Conservatives could be the best tactic for the Lib Dems under AV

If you use the delightful Electoral Calculus to ‘predict’ the 2015 UK general election result using the latest opinion-poll figures from ComRes, there’s very little variation whether you use the First Past the Post (FPTP) or Alternative Vote (AV) electoral systems. According to ComRes, the current voting intentions across the UK would be Labour 40%, Conservative 36% and Lib Dem 10%. Using FPTP without factoring in any tactical-voting swings between the parties, and on the basis of existing constituencies, Labour gains an overall majority of 40 while the Lib Dems drop to only 14 seats. Using AV still gives Labour a majority of 30 but helps the Lib Dems to 32 seats: much better, but still way below the 65 seats that would be proportional to their vote share.

Factoring in a 5% tactical-voting swing from the Conservatives to the Lib Dems doesn’t change the result. However, Electoral Calculus doesn’t allow you to factor in a tactical-voting swing from the Lib Dems to the Tories. On the basis of the Electoral Calculus prediction – however unreliable it may be – I would say that the best thing Lib Dem voters could do to prevent an outright Labour win would be to give their second preferences to the Tory candidates wherever they stand a chance of beating Labour.

This runs slightly contrary to my previous post on AV tactical voting, where I assumed that Lib Dem voters would be reluctant to give their second preferences to the Conservatives in seats of this sort in the context of a Labour resurgence. However, if the aim is to prevent an overall Labour majority, this makes absolute sense – just as it makes sense for Conservative voters to indicate the Lib Dem candidate as a higher preference than the Tory candidate in seats of this sort in order to defeat Labour, on the basis that Lib Dem voters couldn’t be trusted to give the Tories enough second preferences to win. Obviously, if it emerged during the campaign that doing so would be the best means for the Lib Dems to keep out Labour, then the tactical rationale would change.

Ironically, if Labour were thwarted from winning an overall majority by this tactic, then the Lib Dems would be in a much better position to form a coalition with Labour as the largest party. The same tactic would apply under FPTP, except that Lib Dem voters would have only one sensible choice: the Tories. In other words, if Lib Dem voters in Tory-Labour swing seats want a coalition with Labour, they’d be better off voting Tory as their only choice under FPTP, and as their second preference under AV, rather than voting Labour! Such is the bonkers logic of single member-constituency parliaments elected by either system!

If you enter more realistic predictions of the parties’ vote shares in 2015, you get a hung parliament under either system, the only difference being the number of Lib Dem seats. I would consider a 35% share of the vote for both Labour and the Tories to be more realistic, with the Lib Dems recovering to 20%. On this basis, Labour emerges as the largest party under both systems, with the Lib Dems gaining 45 seats under FPTP and 65 under AV.

If you enter lower vote shares for the major parties – on the basis that AV is supposed to encourage voters to opt for minor parties as their first preference – there’s virtually no change to this picture. Assuming a 32% share of first preferences for both Labour and the Tories, and 16% for the Lib Dems, Labour is still the largest party and the Lib Dems win 63 seats. Minor parties pick up only one seat, and that’s not Caroline Lucas for the Greens in Brighton Pavilion, who is predicted to lose her seat to Labour. So much for AV fostering political pluralism!


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