The national swing to the Conservatives is would be enough to give them an absolute majority, if it was reflected evenly across the country, but it won't be. Crucially, Scotland seems to be pretty much where it was in 2005 (2). Wales seems to show a bit more movement (3), but that's the volatile welsh temperament for you ...
What this means is that Labour will retain most of their Scottish and Welsh seats - where they are massively the majority party, albeit on a minority of the total vote - and this will give them the numbers to deny the Tories an overall majority.
It would be interesting to see polling across the regions in England as well. It seems likely that the North of England will mirror Scotland, and the swing to the conservatives will be lower than the national figure. So the Conservatives will comfortably win seats in the south, but struggle the further north you go. Whether their gains in the south will compensate for their rebuff in the north is anyone's guess. Mine is that it won't be.
So, on Friday, I predict we'll be looking at ...
Conservatives ... 284 seats
Labour ... 250
Liberal Democrats ... 83
Scottish National Party ... 8
Plaid Cymru ... 4
Others ... 21
Which leaves the Conservatives 42 seats short of a majority. Even allowing the Tories a 40% share of the English vote - well above anything they are polling - won't get them there.
Of Labour's 250 seats, 34 would be Scottish, and 23 Welsh. The 'Others' are not specified. I had ratcheted down the percentage given to 'Others' to what I thought was a realistic level - allowing the Greens to win in Brighton, and allowing for another couple of independents. I assume the remainder must represent the Ulster contingent. Obviously, Irish politics is deemed to Byzantine for outsiders to make any sort of predictions about it ...
My gut would be that, if the results on the day are around these numbers, the likelihood is a Lib-Lab pact. Gordon Brown hangs on as Prime Minister, Nick Clegg gets to be home or foreign secretary and Vince Cable gets a subordinate financial, with Alastair Darling retaining the chancellorship.
Interestingly, the long term impact would be to destroy Labour's control in Scotland. Opposition there is divided between the SNP and the Liberal democrats, and Labour have enjoyed the benefits of this disunity, returning more MPs than their share of the vote would suggest. Any deal with the Liberal Democrats would have electoral reform as a requirement, however, so in future the Liberal and National presence north of the border would be strengthened - and Scottish Tories would finally get a look in after 13 years of almost complete shut-out.
Interestingly, this is what my head is telling me. My gut says that on Friday morning, unfortunately, David Cameron will have a slender over all majority. Because life sucks, and then you elect a Tory ...
1 - UK Polling Report's advanced swingometer, as of 5th of May, 2010. (http://ukpollingreport.co.uk/blog/advanced-swingometer-map)
2 - "More from Sunday's polls," by Anthony Wells. Posted on UK Polling Report, 2nd of May, 2010. (http://ukpollingreport.co.uk/blog/archives/2668)
3 - "You Gov poll of Wales," by Anthony Wells. Posted on UK Polling Report, 4th of May, 2010. (http://ukpollingreport.co.uk/blog/archives/2679)