What if Tories tactically vote on the same scale as Labour supporters?

All the projections, like the ones on UK Polling Report and ElectoralCalculus, on how specific poll ratings would translate into Commons seats are based on the notion of a uniform national swing (UNS). These show, broadly that just to be ahead on seats the Tories need a 5% margin on votes nationally and to get a majority then they should be aiming for a 10% lead.

But all these calculators do is apply mathematical formulae to the 2005 results adjusted for the boundary changes. The core assumption is that in other respects things will operate like they did on 05/05/05. But what happens if they don’t? Could that make a difference to Labour’s safety nets?

In the second of a series of articles questioning the robustness of those 5% and 10% margins we look at the possible impact of more tactical voting by Tory supporters in order to stop Labour.

What if the the desire to get Labour out next time causes more Tory voters to switch to the Lib Dems in certain seats – just like Labour supporters did in 1997, 2001 and 2005 to impede the Tories?

For last time this seemed to work so much better for Labour because of a reluctance of Conservative supporters to switch to the Lib Dems in order to stop Labour on the same scale.

As part of his Gap Analysis as to of why Labour seem to get so many more seats for votes cast than the other parties Martin Baxter shows that the effect of Labour supporters being much more ready to vote tactically is almost as important an element as unequal seat sizes in giving Brown-Blair’s party its boost.

This is how he describes it: “An informative statistic is that in the 18 Conservative marginal seats, where Labour was third, the Labour vote averaged just 12.04% and the Conservatives only won 2 of those seats. But in the 16 Labour marginal seats, where the Conservatives were third, the Conservative vote averaged 17.81% and Labour won 13 of the seats.

It appears as if Labour supporters are quite ready, if Labour is trailing, to vote tactically to support the Lib Dems against the Conservatives. But Conservatives are less inclined to vote Lib Dem to stop Labour. So tactical voting by Labour supporters could be worth about 10 seats of the gap.”

So for next time there are three big questions:-

Will Labour supporters vote tactically to the same extent that they did last time to keep the Tories out? Almost certainly

Will Tory supporters be more ready to vote Lib Dem in seats like Manchester Withington that Ming’s party will be defending against Labour? This must be highly likely

And will the possibility of more Tory tactical voting open up new possibilities for the Lib Dems against Labour incumbents? Possibly.

In addition a reluctance for Lib Dem supporters to go on helping Labour (tactical unwind) helped the Tories win more seats than the UNS predicted in 2005. Will that trend be accentuated next time? Probably.

CON > LD tactical voting would not help the Tories get a majority but it would not impede Cameron’s party either. What it would do is make it that much harder for Labour to stay in power or even, in a hung parliament situation, to be ahead on seats.

Adding all of this up my guess is that Labour’s tactical voting advantage of 10 seats will be a lot less than last time if it exists at all and this could have a big impact on the overall result.

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Mike Smithson