The government is still not prepared to admit the real cost of the Olympics, but treating us like children and hoping that nobody will notice when it creeps towards £12bn is asking for trouble

In some ways you have to feel a little sorry for Tessa Jowell. The role of minister for culture, media and sport has never been one of the great offices of state. Fun, yes. Stimulating, without doubt. But frankly it has never had the gravitas of the Treasury or the prestige of the Foreign Office or even the credibility of Environment. No, culture, media and sport is about attending the cup final, keeping an eye on the lottery and ensuring that Live 8 finishes on time.

Then on one lunchtime in July 2005 everything changed. Jowell suddenly became the political face of one of the most exposed, risk-laden and economically challenged projects the UK has undertaken in modern times – the Olympic Games.

I have it on good authority from one of those close to the action in Singapore that the UK delegation, so elated at the time, was also stunned that the decision had gone their way. It was like wishing for a gift so outrageous in its magnitude that you never really expect to get it and certainly don’t have a plan for where to put it if you do.

Which leads me to the elephant in Jowell’s office. There have been gasps of surprise and calls for investigation as the budget has doubled and trebled to about £9bn. What is bizarre is that nobody has the courage to admit what Jack Lemley stated in the first few months, that the final cost is likely to be about £12bn.

This leaves us with two questions. Have we learned nothing from Wembley or overruns at other venues? And, more significantly, how can a fund for “unknown contingencies” stand at the rather precise figure of £2.5bn – isn’t that a worrying contradiction in terms?

I do not accuse my fellow consultants of getting their sums wrong, but frankly Harry Potter stands as much chance of magicking up a realistic budget for the Olympics as the cost managers placed between the competing forces of media-gripped politicians and paranoid bureaucrats at the International Olympic Committee (IOC).

What is bizarre is that nobody has the courage to admit that the cost is far more likely to be about £12bn

I believe that £12bn is actually a pretty good deal for a six-year project that will not only regenerate east London but provide a fantastic marketing platform for UK plc. It is the equivalent of 12 Domes, or a small percentage of the government’s five-year forecast. Put another way, it is nearly the equivalent of the £11bn surplus predicted by Gordon Brown in the Budget for the current economic cycle. If you’re lucky enough to have a surplus, why not invest in the Olympics?

So if it looks like it is a good investment and we know its going to happen, why is it so difficult for those involved to treat the taxpayers of the UK as anything other than small children whom they are afraid will discover the truth about Santa Claus? It’s the we-can-tell-them-in-the-end-but-let’s-drag-out-the-fantasy-for-as-long-as-possible approach to budgeting.

The issue with which the IOC needs to grapple is more fundamental than the cost issues in the UK. With a predicted £35bn being spent on the Beijing Olympics, the original concept of the Games is in danger of vanishing amid a global peeing contest by the super nations. How can we expect to see an African or South American-hosted Games when even £12bn looks a bit like a bargain-basement Olympics?

Having worked in the built environment all over the world for more than 30 years, I like to think that I have a fair grasp of the realities of managing projects, whether large or small, sophisticated or simplistic, iconic or ironic. If there is one thing that is true to all, it is that the original estimate when welded to a changing specification bears no relation to the final bill. It is best to keep the client informed before it gets the bill rather than hope that everything somehow works out afterwards.

The IOC may wish to consider fixed-cost Olympics – where the budget is set and bids are evaluated on merit rather than size of chequebook. Until that day, the best we can hope for is that the UK government treats us as adults and gives us a realistic budget.