Labour-SNP coalition adds up (if you ignore Trident issue)
Projection says this is the only pairing that can win a majority – but Labour won’t budge on Trident

Labour will not support the scrapping of Trident in order to form a coalition with the Scottish Nationalists, should they be the biggest party in a hung parliament on 8 May.
Ed Miliband’s campaign chief Douglas Alexander told Andrew Marr yesterday: “It’s the responsibility of a Labour government to keep this country safe.” As the likely Foreign Secretary if Labour win power, Alexander added: “Our position on Trident is clear and I’m not changing it.”
Alexander did not categorically rule out an election pact of some sort with the SNP. But abandoning the replacement of the nuclear deterrent would not be up for negotiation, he insisted, and nor would Sturgeon’s other demand – that Scotland be given full fiscal autonomy.
Alexander’s tough talk came as Electoral Calculus released a projection that a Labour-SNP pairing is the only combination of parties that would cross the threshold of 326 seats necessary for a Commons majority.
The projection is based on current polling averages which have the Conservatives and Labour neck and neck and the Lib Dems set to retain barely a third of the support they enjoyed in 2010.
According to the projection, Labour would have 297 MPs and the Tories only 265. The Lib Dems would shrink to 17 MPs and the Scottish Nationalists would jump from six to 47. On that basis, the Tories and Lib Dems would be able to muster only 282 MPs – way off the necessary 326. But the Labour-SNP pairing would have 344, enough for a majority.
Before anyone gets too excited – or alarmed – the Electoral Calculus projection was not the only one released this weekend. A second forecast comes from Professor Paul Whiteley at the University of Essex, a former director of the British Election Study – and it suggests a very different outcome.
Whiteley gives Labour a much narrower lead – 291 to the Tories’ 281 – and crucially he believes the Lib Dems will do much better than most observers give them credit for and the Scots Nationalists much worse. He sees Nick Clegg’s party holding on to 48 of their current 57 seats whereas the SNP would struggle to get into double figures.
As a result, under Whiteley’s projection the Lib Dems would have a choice of coalition partners: a pairing with Labour would total 339 MPs - a Commons majority of 14. A Tory-Lib Dem coalition would muster 329 - a majority of just three.
Whiteley admits that the SNP are a “wild card” but he suggests they won’t do as well as recent polls suggest because increasingly Scots see the Westminster election as secondary to the Holyrood poll. He expects turn-out to be lower than in the high-profile Scottish referendum.
His positive forecast for the Lib Dems is based on there being a “stronger incumbent effect for Lib Dem MPs than any other parties, partly due to many of their MPs long holding marginal seats”.
So, who's got it right - Electoral Calculus or Prof Whiteley? We should get an idea in the next couple of days when Lord Ashcroft reveals the long-awaited results of his polling in Scottish seats.