Last week, Tony Blair’s holiday host, Silvio Berlusconi, was kicked out of office in Italy. Despite the overwhelming evidence that Mr Berlusconi’s probity is – to put it charitably – in doubt, it was not his alleged corruption which did for him.

He is leaving office for political reasons. Italian voters have had enough of him.

When Mr Blair leaves Number Ten, the opposite may turn out to be true. The Prime Minister long ago lost the support of Labour MPs. If it was up to them, he would by now be history.

But if Mr Blair does leave office much before the end of the current parliament, it may have nothing to do with the loss of political support. It is no longer fanciful to suggest that when he goes, it may because of what emerges when -and if he has to help Scotland Yard with their enquiries.

When a Scottish Nationalist MP, Angus MacNeil, made a complaint to the police about alleged infringements of the Honours (Prevention of Abuses) Act of 1925, it was dismissed by most commentators – and certainly by the government – as a publicity stunt.

But it is now clear that the police are taking their duty to investigate extremely seriously. A fact demonstrated by last Thursday’s arrest of Des Smith, a former adviser to the government on city academies, who was caught on tape by an undercover reporter promising honours and peerages in return for cash donations to support academies.

As the Watergate scandal showed, seemingly trivial or obscure events can unravel with unimaginable consequences. A small break-in at the Democratic Party office in the Watergate building was a minor story which was barely noticed at the time. But when two reporters started to investigate the events, they uncovered a scandal which led to the resignation of the President.

The event which triggered the current police investigation into Labour’s alleged corruption was equally trivial. Speaking in the Commons one day, Geoff Hoon, the Leader of the House, laughed off with disdain the ‘coincidence’ of big donors to the Labour Party also being awarded peerages.

Despite his title, Mr Hoon is a minor political figure of no real importance. However, his arrogant dismissal of the blatant corruption which lies behind Labour’s award of honours so enraged Mr MacNeil that he made his pivotal complaint to the police.

Even without that, the newspapers would still be full of what have become almost daily revelations. But this government is well versed at brushing aside exposes of its members’ behaviour.

News reports and investigations are one thing. A police enquiry, however, is of an altogether different order of importance, with consequences out of the government’s hands.

The police have not – yet – been entirely nobbled by the government. And tumbleweed-like, the complaint of an obscure Scottish Nationalist MP has unleashed an inquiry which could expose the very heart of Labour’s darkness.

Police have apparently seized Cabinet Office papers and emails. It is clear that they are determined to get to the bottom of the issue. They are intent on interviewing Lord Levy, the Prime Minister’s chief fundraiser (nicknamed Lord Cashpoint), and it is clear that they are determined to get to the bottom of the issue.

So what might Lord Levy tell them?

It is no longer possible to say with weary cynicism that the police’s investigation will lead to prosecutions. There is, however, a growing sense of anticipation within the Westminster village that the police could be on the point of uncovering hard evidence of Labour’s corruption.

If that is indeed so, the smug British view that our system is superior to corrupt continental politics will be seen for the delusion that it is. The likes of Jacques Chirac and Silvio Berlusconi may – rightly - be condemned for their venality, and for clinging to office to avoid prosecution, but we have a government which has introduced its own form of corruption into the fabric of politics.
What is most damning about the tape recorded words of Des Smith is that he makes explicit what has long been regarded as implicit in the honours system: that there is a menu with prices.
In his conversation with the undercover reporter, he said that a donor who gave to “one or two” academies might be given an OBE or a knighthood, and one who supported five would be “a certainty” for a peerage.
When the reporter feigned surprise - “Really? Just for getting involved with the academies?” – Smith replied: “Just for, yes, they call them ‘services to education’”.
He went on: “Oh yeah, yeah . . . it’s a nomination and then the prime minister would write to somebody and say we’re thinking of nominating you, but we’ll choose the honour.
It will either be an OBE, a CBE or a knighthood . . . But also what would be great is, you could go to the House of Lords and . . . become a lord.”
The Government says, in effect, that Mr Smith was hallucinating and that his claims are nonsense. The proof of the pudding, however, is in the eating, and the nominations for peerages and other honours bear out what Mr Smith said.
Only this weekend, the Government was forced to admit that two donors – Sir David Garrard and Barry Townsley - were nominated because of their support for academies.
Some will say, with good reason, that it is entirely appropriate that philanthropists who give money to fund education are put forward for honours.
Indeed. But where does that leave the realms of desirable public acknowledgment for charitable behaviour, and enter the realms of corruption of the political process?
The words of a senior Downing Street source, quoted yesterday are particularly revealing: “What we wanted was people with expertise in academies as working peers, taking the Labour whip, who could actively contribute with a massive amount of knowledge to the debate on education in the House of Lords.”
In other words, the Government was appointing as peers the donors who made the existence of academies possible, with a vested interest in their success, specifically in order to influence votes in the upper chamber.

If that is not corruption of the political process, what is?

I have used the word ‘Government’ here somewhat coyly. In this context, by ‘Government’ one really means just one person: Tony Blair.

Academies are one of the Prime Minister’s flagship policies. And the funding of academies is simply one aspect of the corruption at the heart of Mr Blair’s abuse of the honours system. Perhaps still more shady is the funding of the Labour Party itself

You do not have to take my word to pin this at Mr Blair’s door. Yesterday, sources close to Lord Levy suggested to one Sunday newspaper that he was against the large secret loans which funded Labour, but that he was urged by Mr Blair to accept them.

The Prime Minister appears to hold the rest of the country in contempt, expecting us to believe that the fact that large donors to Labour and Labour projects end up in the House of Lords is entirely coincidental.

Well, Mr Blair, we were not all born yesterday. When something appears blindingly obvious, it is more often than not because it is true.

If the police unearth hard evidence of Labour’s corruption of politics, we will soon be in the midst of the greatest political scandal of modern times.

But even if the police are unable to find enough evidence to prosecute anyone, it will not mean the stench of corruption has disappeared. There does not need to have been criminal wrongdoing for there to have been political wrongdoing.

And we already have more than enough evidence to show that the Prime Minister is up to his neck in that.