Conservative strategists have been hoping for a pro-government swing in the polls, as has often happened before. Indeed they have been patiently waiting for the last year, without much success. One is reminded of the followers of the Great Prophet Zarquon in Douglas Adams' Hitch-Hikers' Guide, who faithfully wait for his re-appearance until the end of the universe.
This weekend's Electoral Calculus poll of polls puts the Conservatives and Labour exactly equal on 33 per cent each, which would translate into a Labour/SNP alliance at Westminster with Ed Miliband as Prime Minister. But to be fair to the swing-believers, there has been some movement in the difference between Conservative and Labour vote shares.
The chart shows not just the poll-of-polls but also its rolling average --- a poll-of-poll-of-polls. This statistical microscope reveals a modest swing to the Conservatives. Three months ago the Labour lead was around two per cent. The gap had narrowed to one per cent by a month ago. In the last month it has shrunk further and practically vanished. But the Conservatives need a lead of six per cent just to continue in coalition with the Liberal Democrats. And there is only one month to go until the election.
Of course, polls are not everything. Another way of estimating the election result is to look at betting market prices. These reflect the opinions of politically informed people who are prepared to back their opinions with their own cash. The current seat market from Sporting Index has Con 286, Lab 270, Lib Dem 24, SNP 42, which translates into a Conservative lead of three and a half per cent. That's a bit better for the Tories than the polls suggest, but it still leaves the election in the no-man's-land where neither Con+LibDem nor Lab+SNP has a majority.
Electoral Calculus uses a weighted blend of these polls and betting market data to make a more accurate prediction. This method currently shows a Conservative lead of one per cent, which still translates into a Lab/SNP alliance.
The second graphic is a revised version of the "electoral battleground" map, showing the possible outcomes of the general election depending on the Conservative and Labour national support levels. Recent history is shown by a linked sequence of blue dots. The current position, marked "April 2015", is in the "Nat choice of Con/Lab" which probably means a Lab/SNP alliance. Back in January, this dot was at the edges of the "Lab choice of Lib/Nat" region, but it has drifted towards the Conservatives since then. The Conservatives still need to cross the "Con/Nat coalition" (which is really a no-man's-land of minority government) before they can come into a majority with or without the Liberal Democrats.
Ultimately Zarquon did appear but too late to do anything before the universe ended. The odds are lengthening against a pro-government swing arriving in time to give the Conservatives a majority.