Who will win the election? That’s hard to answer and anyway it’s the wrong question. Who will be prime minister after it? That’s easier: David Cameron.

As we enter 2010, it has dawned on the markets at least that a hung parliament is a strong possibility. The expectation that the Conservatives could win with a majority is being revised down as analysts register that for Cameron to achieve outright victory he would need a huge swing (although not as large as that achieved by Tony Blair in 1997).

As things stand today, Cameron commands 193 seats in a Commons of 646. He has fewer seats than Michael Foot had in 1983 and it took Labour until 1997 to return to government from such a profound deficit. The Tories face an uphill struggle, not least because their vote falls inefficiently, piled up in safe seats rather than spread around helping them to win more. At the 2005 election they polled only three percentage points less of the vote than Labour did, but their tally of seats was 157 smaller.

The big difference between the Commons today and 20 years ago is the rise in the representation of the minority parties. If you exclude Sinn Fein, which has not occupied its five seats, there are 94 MPs who are neither Labour nor Conservative. On paper, therefore, a broad range of possible outcomes at the next election delivers a House of Commons in which no party has a plurality of seats.

A good question to ask is: is it likely that Labour will lose its overall majority? Yes, it almost certainly will. That requires the loss of only 32 seats and 41 are vulnerable to the Tories on a swing of three points or less. Just now the Tory lead in opinion polls averages about 11 points, which indicates a swing of seven points since the last election. So even if the Conservative lead narrows markedly between now and election day, Labour seems doomed to lose its overall advantage.

Are the Conservatives likely to gain 128 seats? That is the number they need to add to their present score in order to hold 321, just more than half the number of voting MPs that there will be in a slightly enlarged House of Commons after the election. In theory that would be achieved with a swing of just below seven points and boundary changes help them; so if everything remained exactly as it is now they might, or might not, make it.

We do not need to be sure of such a dramatic change in political fortunes to be fairly confident that Cameron will be invited to kiss the Queen’s hand. If Labour fails to secure a majority — even if it wins more seats than the Conservatives — it ought to be booted out and in all likelihood would be.

To govern, it would need the support of a smaller party and it seems implausible that any of them would be willing to prop up a government that has been dying on its feet for years and has led Britain into the longest recession since records began. It would be especially difficult for the Liberal Democrats to support Labour if it had lost to the Tories in terms of the popular vote — the number of actual votes cast — which seems all but certain.

An interesting precedent was set after the last election to the Scottish parliament. The Scottish National party (SNP) led Labour by a single seat and secured just 47 seats in a house of 129. But the previous coalition between Labour and the Lib Dems had clearly failed to “win” and so the SNP has been allowed to govern as a minority.

Unlike Gordon Brown, Cameron does not need third-party support to be in office. If, like the SNP, the Conservatives go it alone, there will be great pressure on the other parties to let them “have a go” without being voted down. It would be very risky for the Lib Dems to antagonise the voters by causing a second election at a time when the public finances need firm government action.

For Cameron, the price the Lib Dems would demand to join him in a coalition is too high. He cannot concede proportional representation, which would be disastrous for both main parties; nor can he accept Vince Cable as his chancellor, because his bond with George Osborne is the Tories’ greatest strength.

So, Cameron it will be, governing alone, with or without a majority. Predicting the exact result is made more difficult because the turnout is highly uncertain. Low percentages voting in 2001 and 2005 led commentators to say that the electorate had become apathetic. But the high ballot in 1992, not a year noted for political enthusiasm among the public, suggests that people bother to vote when the result is in doubt, as it will be in 2010.

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