Peter Kellner of YouGov describes how Cameron can win next time with a single-figure majority

By Paul Goodman
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In last weekend's Sunday Telegraph, the foundation of my article arguing that David Cameron won't win an overall majority in 2015 was a estimate made by Peter Kellner of YouGov.

He has previously set out why Mr Cameron needs a seven point lead over Labour to gain one - which, I believe, the Prime Minister can't achieve: I quoted the figure.

Today, Kellner has published an ingenious piece explaining how the Conservative leader can win with a majority of (by my count)...five.

But in Kellner's imaginary scenario, the poll lead Mr Cameron achieves in 2015 is one of only four points.  So how does the Prime Minister do it?

According to Mr Kellner, by picking up 24 seats from the Liberal Democrats and losing none to Labour.  It is exactly the kind of 1992 campaign that Mr Cameron will surely aim to fight.

Kellner's vote shares are: Conservative 39%, Labour 35%, the Lib Dems 13%, UKIP 4%, others 9%.  It is very clever, but I don't quite buy it.  What do you think?

Tim Montgomerie's response to my piece, arguing that victory isn't impossible, can be read here.