Why an electoral pact between the Coalition partners isn't as simple as it may seem to be

By Paul Goodman

Nick Boles proposes a pact between the two Coalition partners at the next general election in today's Times (£).  Essentially, he suggests that if the number of constituencies is reduced and First-Past-The-Post still applies...

• The Conservatives and Liberal Democrats divide the seats that each party now holds (or would have held had the forthcoming boundary changes been in place last May).
• Liberal Democrat candidates withdraw from Conservative-held seats.
• Conservative candidates withdraw from Liberal Democrat-held seats.
• Liberal Democrat candidates withdraw from Labour-held seats in which the Conservatives came second at the last election.
• Conservative candidates withdraw from Labour-held seats in which the Liberal Democrats came second at the last election.

Such a pact may or may not be good in principle (as it happens, I'm not unsympathetic to the idea).  But it's harder to achieve in practice than is apparent at first sight.  Here are some reasons why.

• If Conservatives and Liberal Democrats divide the seats that each party now holds (or would have held had the boundary changes been in place last May), and withdraw candidates in the way that Boles suggests, the move won't win the Coalition a single extra seat.  This may be a bit obvious, but it's worth saying at the start.
• The phrase "would have held had the boundary changes been in place last May" begs a lot of questions.  Can we really know now what the boundary changes will look like?  If seats are drawn with very different boundaries from the present ones, how can one always be sure who'd have held what?  What assumptions can and should be made, for example, about the Liberal Democrat MP who presently commands a good majority in Baskerville North - but whose seat is abolished under the change, and is selected by local party members to contest Baskerville South?  Should the Conservatives simply assume that he'd have won Baskerville South - previously part of a very blue seat?  And, by extension, what assumptions should and can be made about the Conservative MP who presently commands a good majority in Baskerville East, but whose seat is...(but you get the rest).
• Boles is assuming that in the Labour-held seats from which each of the Coalition parties withdraws, those who've voted for one of them will support the other.  My guess - and it's no more than a guess - is that Conservative voters in such seats are more likely to support the Liberal Democrats than Liberal Democrat voters are to support the Conservatives.  This is because the prospect for Liberal Democrat voters of supporting for dreaded Tories may be too big an ask - even when a electoral pact between the two parties applies.  Labour could therefore, in Labour/Conservative marginals, actually gain more votes than they otherwise would have done.

As I say, I'm not unsympathetic to the idea of a pact.  I'm simply pointing out that it's more problematic than may seem to be the case at first glance.  And that's before trying to calculate what would happen if AV applies.

> 55% of Tory members are open to non-aggression pact in Lib/Con marginals