PFI has paid for schools, hospitals and roads
Panorama's John Ware analyses the government's dilemma - and the hidden pricetag - in turning to the private sector to fund Britain's much-needed public infrastructure.
What really lies behind Tuesday's expected announcement by the chancellor in his Autumn mini-budget of a £30bn investment fund?
Partly it is to rebuild Britain's creaking infrastructure, especially with transport and energy projects.
Clearly, George Osborne also hopes it will resuscitate the flat lining heart of our economy into a bit of growth.
But there is something more.
It is also a glimpse of what might emerge from his recently announced review into the highly controversial Private Finance Initiative - known as PFI.
The Treasury has told tonight's Panorama investigation into PFI deals that the review will see the "end of PFI as we know it".
Find out more
John Ware presents Panorama: Who's Getting Rich On Your Money?
BBC One, Monday, 28 November at 8.30pm
PFI is the mechanism by which the private sector has been encouraged by the Treasury to design, build, finance and manage a growing number of public sector projects - now numbering over 1000 hospitals, schools, and many prisons, roads and defence contracts.
In return the taxpayer pays annual fees to PFI companies over the contract period, which on average last about 30 years.
But what exactly does the Treasury mean by "the end of PFI as we know it"?
Presumably the end of PFI as the "goose that laid the golden eggs" as former Treasury mandarin Sir Steve Robson once put it to the City.
And it is true that, for some investors, PFI has been a gravy train. They have made hundreds of millions from refinancing deals and sale of their equity.
For years the Treasury has argued that PFI provides better value for money for the taxpayer for large infrastructure projects than if they were funded directly by government borrowing.
'We will all pay later'
But over the summer MPs on both the Treasury Committee and the Public Accounts Committee challenged that claim - especially since the credit crunch has meant government borrowing is half the cost of private borrowing.
But will the "end of PFI as we know it" also mean the end of what both the Prime Minister David Cameron and Chancellor George Osborne referred to in opposition as "dodgy accounting" associated with PFI?
That's a tougher call.
PFI is a like a giant government credit card.
It allows ministers to buy and launch lots of shiny new infrastructure projects - without the bill scoring as debt on the nation's balance sheet.
Instead, just like a credit card, while ministers buy now, we will all pay later.
In fact, over at least a generation or two later.
What Mr Cameron and Mr Osborne meant by "dodgy" was that using PFI in this way flattered the overall picture of our indebtedness as a nation.
They wanted, they said, more transparency.
Yet since coming to office, ministers have signed 34 PFI schemes and another 49 are on their way to being approved.
And that means yet more billions slid onto the PFI credit card.
This includes Health Secretary Andrew Lansley giving the green light to a new PFI hospital in Liverpool costing £1.24bn over 30 years.
That was even though documents obtained by Panorama show that his own officials warned that the "risk" that it might not be able to afford its PFI payments was "significant."
This has not stopped Mr Lansley from complaining loudly recently that PFI deals negotiated under the last Labour government have brought some parts of the NHS to the brink of financial collapse.
Of the £30bn infrastructure investment plan to be announced by the chancellor tomorrow, £20bn is being sought from UK and foreign pension funds.
So why doesn't the chancellor just go out and sell some government gilts which would probably be cheaper?
That is where the PFI review comes in.
Presumably the chancellor will not want this £20bn to show up as debt on the country's national accounts (Public Sector Net Debt).
Whether the £20bn does count as debt will depend on what risk to the pension funds these infrastructure projects pose and that is where the difficulty could arise: pension fund holders want long-term low-risk investments.
They are not going risk their billions unless all the bases have been covered.
And if they require the government to underwrite too much of the risk, the £20bn could end up counting as public debt.
So how the "risk" in these projects ends up being classified is the real nitty-gritty bit of Mr Osborne's investment plan that has yet to be resolved.
With nearly £40bn already hidden on the PFI credit card, were he to honour his pre election pledge to be more transparent about Britain's balance sheet, yet more billions could end up being added to the country's soaring debt - which could torpedo his much prized deficit reduction target of starting to bring down our debt by 2015-2016.
Unfortunately for the chancellor that is also just when PFI payment charges will be almost at their peak.
That is why, with major new infrastructure projects urgently needed, he clearly intends that some form of private finance using a similar mechanism to PFI will continue.
In opposition, the cry for transparency is one thing. In office, the allure of smoke and mirrors can be quite another.
The "end of PFI as we know it" might well be nigh. But the "son of PFI" could also soon be born.
Panorama: Who's getting rich on your money? BBC One, Monday, 28 November at 20:30 GMT and then available in the UK on the