I am passionate about this! cried Tessa Jowell as she gave evidence on the London Olympics to MPs yesterday. And I thought, oh no, give me politicians who are not passionate; give me politicians who can add up.

Like the Chancellor. I bet Gordon Brown is worried and furious about these Games. The extent to which the Treasury trusts the Olympic planners is clear from the fact that they have demanded a contingency fund of 60 per cent of the budget for cost-overruns, compared with a normal construction contract which would require just 20 per cent. London 2012 has, and always did have, the makings of an economic nightmare about it: a massive, unfunded infrastructure project on sites we didn’t yet own, built on land contaminated to a degree we hadn’t yet discovered, with uncertainties from transport to security to, well, everything, but with one unyielding and deadly certainty to it: we had to do it by the summer of 2012, a fixed and extremely brief timescale.

Yesterday Ms Jowell, Secretary of State for Culture, Media and Sport and political leader of the Games, admitted that costs for the Olympic park had risen 40 per cent in a year. It will now cost not the £2.375 billion of public money she promised last year that she was applying “absolute rigour” to, but £3.3 billion of public money. Then there is another £1.044 billion for regenerating the East End. London Assembly members, who meet today to discuss the Olympics budget, think it may cost £8 billion or more in the end.

Take a figure . . . double it . . . add whatever you like. Which part of the extra costs were not predictable when the bid was submitted in October 2004? A spiralling security budget, more than quadrupled now to £850 million? Did the bid team really need to wait for 7/7 to realise that an Olympics in London in 2012 would be under particular threat from Islamist terrorism? Or was it the increasing cost of land in the East End that took them by surprise, from a predicted £478 million to £1 billion and rising? I wonder who it was who failed to predict that landowners would make sure they squeezed as much as they could from a Government that had no choice but to buy their land, and fast. “We have also adjusted the transport figure to put it in 2012 figures,” Ms Jowell blithely added yesterday. Well, what figures was it in before? And who drew them up? Ah, yes. Tessa Jowell.

It is a horrendous and entirely predictable predicament that the country has got itself into in pursuit of international glory. Ah, say ministers, but this is about regeneration: look what the 1992 Olympics did for Barcelona. But Barcelona needed regeneration; London does not. The East End could do with some help, sure, as could some other cities, but as the Labour MP Alan Keen astutely pointed out yesterday, we could surely have regenerated the area at a less Olympian cost were we not tied into such a firm timescale; in other words were landowners and the construction industry not able to hold the Government to ransom.

No, says Ms Jowell, but this is for the children too: hundreds of thousands of them around the country inspired to sporting success! (And here her voice got quite emotional.) “Go into any primary classroom in this country and talk to any of the children,” she urged. No fewer than two thirds of nine to 11-year-olds think they are going to take part in the Games, “half think they are going to be medal winners!” Well she must be talking to different nine-year-olds to me because I haven’t met any who think that.

And if I did, I would be rather angry: what kind of unrealistic ambition is that? My local nine to 11-year-olds would be a lot better served by getting the comprehensive they all have to go to in the next few years out of special measures. You can’t be against improving sport in schools, but we do not need the Olympics, and all that money wasted, for that to happen.

Because it is money wasted, yours and mine. Whether it comes from the lottery or the London council tax, the Treasury or a “VAT rebate”, this is public money, billions and billions of it, that could have been better spent elsewhere.

You can tell when ministers have become misty-eyed over something just because it’s big: Ms Jowell kept referring in awe yesterday to “rigs” and “drilling” and “undergrounding of power lines”. There are 450 people demolishing 53 power lines, she said at one point. So what? You should come and see the “eight drilling rigs” we’ve got. Why? What does it prove? Nothing. This has become a grand narcissistic project.

“I’m saying,” Ms Jowell assured the select committee at one point, “that the Olympic Games will be delivered on time.” Of course they will be. They have to be. That is precisely the problem.

Unless we pull out. It is now clear that London 2012 is going to be a monstrously expensive enterprise of limited benefit to most of the nation. When Jack Lemley, the American construction entrepreneur and Olympic Delivery Authority chairman, resigned last month not wanting to be associated with such a tainted venture, he cautioned that costs would rise exponentially, big projects would be late, and no one could even agree on what the £280 million new stadium should be used for after 2012.

It is criminal to spend so much public money on such idiocy. I asked the International Olympic Committee yesterday what the penalty would be for walking away now. Would Britain be sent to the international version of Coventry, perhaps? The contract signed with the IOC stipulates that we would have to “indemnify” the IOC if we pulled out. Indemnify it for what? It hasn’t cost them anything.

They won’t do it, of course; too many egos invested already, too much national machismo. Five billion pounds and rising . . . Where’s my wallet?

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