"The question David Cameron was asking through election night was not 'Will we get enough seats to win?' but 'Will we get to 300?',", the Conservative Party pollster Andrew Cooper of Populus, a key insider at Tory campaign HQ, told a general election "inquest" panel debate in Westminster last night.
Cooper was speaking at the launch of The British General Election of 2010, the latest indispensable edition in the unparalleled series of election books, now written by Philip Cowley and Dennis Kavanagh. (The books were long nicknamed the "Nuffield" series after the Oxford psephological legend David Butler, of Nuffield College, an author on every study from 1945 to 2005, who attended last night's launch of the first book he was not involved in writing).
Cooper's account of Cameron's lack of electoral self-confidence is captured in a telling election-day vignette of the Cameron kitchen cabinet from Cowley and Kavanagh's book:
On the morning of polling day Cameron's team sat round Steve Hilton's kitchen table in Oxfordshire and made their predictions; most were for the Conservatives being the largest party but without a majority.
The authoritatively sourced book, based on 360 insider interviews, does not take a punt on who predicted what.
What seems clear is that both David Cameron and George Osborne were among those predicting a hung parliament. Informed speculation in Westminster suggests that their predictions were pretty similar, but that Osborne may have been marginally closer to the final tally. (I have heard, though cannot verify, that Cameron predicted 311 Tory seats and Osborne 308, almost exactly hitting the 306 seats the party won on the night; the Tories finally ended on 307 after the delayed Thirsk and Maldon contest later in May.)
Perhaps, almost six months on, we might now be at a distance safe enough for the political lobby to find out how the rest of the kitchen cabinet fared in the election-day guessing game. Cameron and Osborne could gain credit for their uncannily accurate reading of the public mood and the electoral map, even in the heat of battle. The downside is the lack of electoral self-confidence at the very top of the party in their own strategy to win, somewhat contrasting with the more bullish mood of campaign staffers and activists.
Cowley and Kavanagh write that the highly accurate BBC/ITN/Sky exit poll (Con 307, Lab 255, Lib 59) "was met with disbelief by most commentators and those in the campaign HQs". That was certainly true of the Tory campaign HQ troops, but somewhat less so at the very apex of the high command, though all parties had expected the Lib Dems to gain rather than lose seats.
For Cooper, the most telling poll finding of the campaign was that 75 per cent of voters believed it was time for a change from Labour, but only 34 per cent believed it was time for a change from Labour and to the Conservatives, a point also made in the book.
He said last night that the strategic weakness of the Tory campaign was always to respond with an "unremittingly negative" attack on Gordon Brown, which failed to take on board how far the decisive electoral question remained voters' doubts about the Conservatives. This meant that they failed to secure enough support – most notably in Scotland, in London (particularly among non-white voters), and among public-sector workers and the less well-off, where those who agreed it was time for a change remained repelled by the risk of the "same old Tories".
As the Tory leadership realised this, they began to make "much more detailed preparations for a hung parliament than anybody realised", Cooper said. That the lack of depth of its "brand decontamination" effort over the five-year parliament was the party's critical weakness was well understood by the leadership in the second half of the parliament.
Indeed, this failing kept David Cameron awake at nights – a detail that captures why the Conservatives are so exercised (as are the Lib Dems) about the Institute for Fiscal Studies analysis showing that their Budget and Spending Review are regressive. As Cowley and Kavanagh report:
Populus developed mood boards to study the Conservative and Labour images and reported each quarter. The most worrying finding for the Conservatives was the perception that they would, in a crunch, stick up for rich and privileged people. Cameron privately confessed late in 2008 that the persistence of this last image kept him awake at night. It was a factor in his shadow cabinet reshuffle in 2009. That the perception declined only slightly by the time the election was called reflected the limits of Cameron's brand decontamination strategy.
This was never resolved, partly as no choice was ever made between competing strategies and instincts of George Osborne, Steve Hilton and Andy Coulson. Ultimately, somewhat by default, Cameron leaned closest to the Coulson focus on tough daily newslines, concentrating on the failure to articulate the Tory alternative. So the book reports Cameron texting the inner circle, after an inconclusive session around the time of the spring conference at the end of February, that the "navel-gazing" about Tory messaging was unhelpful. The answer was to focus more relentlessly on "change" and Gordon Brown's record.
Cameron's lack of electoral confidence is also relevant to the prevailing assumption that a minority Tory administration would have won a second election – this autumn or next spring. The authors admit that nobody knows what would have happened, but they challenge this orthodoxy (which the Lib Dem leadership often relies on to argue that a supply-and-confidence arrangement would have been much worse than a coalition);
There was no guarantee of winning another quickly held election. In both 1910 and 1974, the last two [occasions] to see two elections in one year, the results barely shifted at the second contest. Moreover, as John Curtice shows [Nuffield appendix], the political geography of the UK has changed in recent years, producing fewer marginal seats and so making a victorious second election even less likely.
Cameron's caution made a coalition sensible. In a parallel political universe  where he had made another choice, his short premiership could have ended this week.
Sunder Katwala is the general secretary of the Fabian Society. He blogs at Next Left .