John Rentoul: I'll put a wager on a Tory victory, despite the known unknowns

I have a confession to make. I owe the Editor money. Nearly two years ago I bet him that Gordon Brown would not be leader of the Labour Party by the time of the election. Well, yesterday was pay day.

That is the thing about events. They don't half get in the way of perfectly reasonable certainties. The last time I laid a bet like that was on John Major to lose office in 1994. And we know what happened then – although it does require some explanation. John Smith died, Tony Blair became Labour leader and stretched the party's opinion-poll lead to 30 points. That should have finished Major off, except that the manner of Smith's death paradoxically drew attention to Michael Heseltine's heart problem, while the other credible Conservative leadership contender, Kenneth Clarke, had stubbornly refused to yield a centimetre to the Europhobics.

This time it was the credit crunch. I was on to a winner until that happened. Just like all those bankers. Even so, it took a while for the political consequences to work themselves through. Brown's reputation recovered a bit in the immediate aftershock, but then fell back and it was not until the past six months that the voters started to focus on the election choice. It was then that fear became a factor. People are worried about their jobs, and about schools and the NHS. And so the Tory lead in the opinion polls started to close.

What was surprising about this was that it suggested that people were listening to the politicians, and paying close attention. They heard David Cameron and George Osborne say that government borrowing was a terrible, terrible problem, and they had drawn the opposite conclusion to the one intended. They were supposed to reward the Conservatives for their honesty and fiscal responsibility and to punish Gordon Brown for his refusal to face up to the problem that he had partly created. That is what last year's game was all about, tying a blindfold on the Prime Minister and making him guess what three-letter word meant "reduce public spending".

The trouble for the Tories was that the voters took them at their word, and decided that the Opposition were more serious about dealing with the deficit than the Government. That would have been fine if the voters thought that public debt was a problem, but the numbers are just too big, and the connection with future inflation too tenuous, for the idea that Alistair Darling is borrowing more in relation to national income than Denis Healey when he went to the IMF to mean anything.

Everyone knows, despite or perhaps because of TV programmes about time-travelling police, that this is not the 1970s. Union leaders may be an irritant but they are not a threat to civilisation as we know it; the rubbish is not piling up in the streets and the dead are, as far as we know, being buried. Yet all the talk of crisis made people worry about their jobs. Folk memory of unemployment still haunts the Tories. And the voters thought not only that Osborne would cut public spending more severely than Labour, which seems like a good idea if you are talking about community outreach awareness facilitators but not so good if you are talking about schools or clinics, but they also thought that the Tories were more likely to put taxes up than Labour. Talk about decontaminating the brand: Cameron was so good at it that for a while there the perceptions of the brands were reversed.

Hence last week's re-reversal. Never mind that the Tory promise not to raise National Insurance contributions is utterly unprincipled, illogical and bad policy. There is an election on. The deficit may not feel real: you cannot see it or touch it, but it is a big problem. It was one of the more impressive positions adopted by Cameron that he was prepared to tell the truth about it to the British people. I am a Labour supporter, but as an admirer of Bill Clinton I am therefore a balanced budget Democrat too. For me, one of the better things that Gordon Brown did was to use the £22bn from selling radio waves that were something to do with 3G mobile phones to pay off some of the national debt. I think Cameron was right that spending has to be cut (and taxes go up) and quickly.

But being right about the deficit was killing Cameron in the polls and demoralising his supporters. The only puzzle is that he and Osborne left it so late to take emergency action. They have ditched one slogan, "We can't go on like this," for another: "Yes, we can."

Brown tried to double-bluff Cameron and Osborne by going to the Palace on the day on which everyone expected him to, but they proved themselves a match for his low political arts. They saw him coming, and took evasive action, just as they did in the autumn of 2007, when his dithering over an early election ended up taking no one by surprise but himself. They proposed a tax cut then and it threw the Government into disarray. Now they propose a tax rise forgone and Ed Balls was on television – never a vote-winner, that – posing as the fiscal conservative, explaining that spending on schools and hospitals has to be paid for.

At which point – the very point when the whole pre-planned non-news story starts to roll – the question of what this election is about suddenly becomes obscure. We have party A promising not to put up taxes, paid for from efficiency savings (the second-to-last refuge of a scoundrel). Against party B promising not to cut "investment" much, paid for by closing eyes and hoping the deficit will go away. Oh, and party C sounding very impatient and saying that we really have had quite enough of this nonsense thank you.

Which means it will be a fascinating election campaign if you like paradoxes. It is exciting in the sense that we do not know what the result is going to be, but not in any other sense. The evidence of previous election campaigns is that nothing much happens to the opinion polls during them. That means an average eight-point Tory lead, give or take a percentage point for the Tory advantage in the marginals and an unknowable variable because we simply do not know how accurate the polls are. Have they over-compensated for their historical tendency to overestimate Labour? What has YouGov done to its methodology since getting the London mayoral election right two years ago? So we know it is going to be close, but we do not know which poll, from Labour the largest party in a hung parliament to a tiny Cameron majority, reflects the state of public opinion as of yesterday.

The televised debates are going to be over-hyped, over-prepped and over-analysed and I bet they won't shift many votes. Yet something else might. Ask the Editor. Something else might disrupt my perfectly reasonable certainty, like Lehman Brothers going under or John Smith dying. So I'm not going to bet with any serious money, you understand. But put me down for a Cameron majority of 16 in the office sweepstake.

John Rentoul is Chief Political Commentator for The Independent on Sunday. He blogs at independent.co.uk/eagleeye