With both this week’s opinion poll and moves on the spread betting markets in the past 24 hours pointing to the General Election producing a big Tory lead on votes but a big Labour lead on seats attention will surely focus on what the Liberal Democrats would do in such an outcome? The Lib Dems can’t duck this one because the mathematics of the next General Election mean that if there is a hung Parliament then the Tories are bound to have at least a 3% lead on votes.

If the Lib Dems had a choice would they support the winner on seats or the winner on votes?

Yesterday’s spread bet moves, in direct response to the way gamblers are investing their money this week, puts the SELL price on Labour within one seat of a hung Parliament.

LAB 325-335 seats
CON 245-255
LIB 52-57

The target for an overall majority is 324 seats. This week’s opinion poll from YouGov, the pollster it should be said that usually shows the highest Tory share, had the following split together with seat estimations from Martin Baxter’s calculator.

LAB 35% 311 seats
CON 39% 265 seats
LIB 19% 41 seats

Thus with 4% fewer votes Labour would have 46 more seats at Westminster– a result that would seem manifestly unjust and unfair to many Liberal Democrats who have been campaigning for decades for a fair voting system that links the way people vote with the number of MPs each party has. The fact that the distribution of Commons seats is so skewed to Labour makes this a much easier question for the Lib Dems to deal with.

However much the party might dislike Michael Howard the Lib Dems have invested so much political capital in a fair voting system that it is inconceivable that they could prop up Labour in these circumstances.

A major factor could be who the Lib Dem leader was to guide the party in this post-General Election aftermath. There’s no doubt from his rhetoric that Charles Kennedy would find it harder than other possible Lib Dem leaders to follow this course. There would be days or even weeks of protracted and tortured debate but the party’s crediblity on such a central plank of its philosophy would be destroyed forever if it backed Labour.

Fair voting and PR have been so much a central and common theme of Lib Dem thinking for so long that as a founder member and former Lib Dem parliamentary candidate myself I find it hard to see how they could support any other course. The Iraq war has made such a stand easier.

There would be a tough negotiation and Howard would have to concede a lot but there is no way that the Lib Dems could prop up a Labour party that had lost to the Tories 35-39% on votes even though it had many more seats at Westminster.