When the third batch of Scottish constituency polls was released by Ashcroft last Friday, there was something of a mystery over what had happened to the polls in Edinburgh North & Leith and Edinburgh South - we'd heard earlier in the week that both seats had been polled by Populus alongside the others. It turns out that they were just taking a little longer to come through, and they've now been published.
Edinburgh North & Leith :
SNP 43% (+33)
Labour 29% (-9)
Conservatives 14% (-1)
Liberal Democrats 6% (-28)
(This would be an SNP gain from Labour. Mark Lazarowicz of Labour would lose his seat.)
Edinburgh South :
SNP 37% (+29)
Labour 34% (-1)
Conservatives 16% (-6)
Liberal Democrats 8% (-26)
(This would be an SNP gain from Labour. Ian Murray of Labour would lose his seat.)
By some definitions, Edinburgh South is one of the two or three toughest seats in the whole of Scotland for the SNP to win - the problem is not just that they need a huge swing from Labour, but in contrast to many western seats they're also starting from a long way behind two other parties. So although the SNP lead Ashcroft is reporting in the seat is small, that tends to confirm rather than detract from the impression given by other constituency polls that if the election was held right now, the SNP would win almost every seat in the country.
The main similarity between today's polls and the three polls last Friday that covered Labour-held seats in the west is that the SNP vote is surging forward by an equally impressive amount - but the main difference is that the Labour vote isn't collapsing to anything like the same extent. (In fact, in Edinburgh South it has barely slipped at all.) Both the similarity and the difference may be a mirage caused by the fact that the Liberal Democrats have been the main challengers to Labour in these two Edinburgh seats in the recent past. The mass desertion of voters from the Lib Dem cause may have benefited both Labour and the SNP, meaning that the true underlying movement between the two main parties is being disguised in the headline numbers. That movement is clearly very dramatic, but not quite as big as in the western seats. In a sense, this bears out the spin we were hearing from Labour a few weeks ago that they were faring better in eastern and affluent seats - but it categorically doesn't bear out their conclusion that they are on course to actually retain those seats. At best, they've got a fighting chance of clinging on.
Edinburgh South is of course always cited as a classic example of the sort of seat where Labour can expect help from Tory supporters voting tactically. There's some evidence of that in the poll, but it's far from overwhelming - the six-point drop in the Tory vote is only a little bigger than the average drop elsewhere.
As always with Ashcroft, it's vitally important to bear in mind two features of the methodology that may be leading to the SNP's true strength being underestimated. Firstly there's the "spiral of silence" adjustment, which artificially reallocates a portion of undecided voters to the party they voted for in 2010. In normal circumstances, that would produce a more accurate result, but the circumstances we find ourselves in are not normal. In both Edinburgh seats, the SNP's lead has been adjusted downwards by 1%.
Secondly and more importantly, the results are weighted by 2010 vote recall, which is known to be unreliable because people get mixed up between their Labour/Lib Dem vote in 2010 and their SNP vote in 2011. In Edinburgh North & Leith, people who recall voting SNP have been downweighted from 118 to 66, and in Edinburgh South they've been downweighted from 97 to 53. Almost a halving in both cases, and you don't need me to tell you that the potential distortion on the headline numbers is massive. It's perfectly possible that the SNP are comfortably ahead in Edinburgh South, as opposed to the wafer-thin lead that is being reported.
The pompously-titled ANP ("Ashcroft National Poll") is also out today, and it's rather wonderful for the SNP. They're on 6% across Britain, and the Scottish subsample figures are : SNP 59%, Labour 15%, Liberal Democrats 11%, Conservatives 10%, UKIP 4%, Greens 0%. As usual, the Scottish sample size is extremely low.
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I've fallen hopelessly in love with the new all-purpose Lib Dem catchphrase. Last week it was "the SNP have taken their eye off the ball", now it's "I've seen the figures". You know the kind of thing - Danny Alexander isn't going to lose his seat because "I've seen the figures". Charles Kennedy most certainly isn't going to lose his seat because "I've seen the figures". And if you think Nick Clegg is going to lose his seat, you're an absolute gibbering imbecile, because "I've seen the figures".
Which figures? Internal comfort polling? Optimistic canvass returns? We don't know, but you can rest assured that there are figures, and they are bloody wonderful for the Liberal Democrats.
I can just picture the scene in East Dunbartonshire in the early hours of May 8th...
Returning Officer : And I hereby declare that the above-mentioned John Nicolson has been duly elected to serve as member of parliament for the East Dunbartonshire constituency.
Jo Swinson : No, he hasn't.
Returning Officer : I'm sorry?
Jo Swinson : I've seen the figures, and he hasn't won. I have.
Returning Officer : I can assure you, Ms Swinson, that we've counted the votes with great care, and Mr Nicolson has more than you.
Jo Swinson : Oh dear, oh dear, oh dear. I think you'll find that the exclusive Liberal Democrat poll that we leaked to the Kirkintilloch Herald tells a rather different story.