I’ve had an idea for a film and I’d like to test it out on you. The tale is a little far-fetched, I admit, but I think the story rocks along nicely.

It starts with a middle-aged politician. He’s a national figure, famous, but just past his peak. You can see the disappointment in his face. It’s one o’clock in the morning and we see our man leaving his favourite restaurant and getting into his modest car. He is heading home.

It is not long before he realises he is being followed. Danger! He screeches to a halt, leaps out of his vehicle, vaults the iron railing and dives for cover in a bed of geraniums. He’s in the nick of time. Seconds later there is sub-machinegun fire. His car is riddled with bullets.

The next day’s front pages tell of the escape. The politician’s coolness is praised, his enemies are described as being capable of anything.

Here comes the twist. A man comes forward to claim responsibility. And more. He says that the politician colluded with him, that the assassination attempt was a fake, designed to boost a flagging career. The politician hotly denies it and everyone believes him. But there is a dramatic resolution to the narrative. The fake assassin had sent a letter to himself before the fateful night. And when the police open it they read the whole story. The exact record of what is to happen — where the car will stop, the geraniums, the lot. The politician is caught.

Good so far? How do you think it should end? I’ll tell you my thought. As the credits roll, you see the face of the politician. The camera pulls back and you realise with a start that he has become President of France.

For the story I have recounted is not fiction. It is not even “inspired by real events”. It is the true story, every word of it, of François Mitterrand.

And we think our stories of dawn raids and interviews under caution are dramatic? That our sneaky politicians are corrupting our national life? Let’s face the truth. We have boy scout politics and the cleanest politicians in the world. Most of the time we have trouble even scaring up a proper sex scandal. I remember it being front-page news when the MP for Finchley went to bed with his research assistant and didn’t sleep with her.

Certainly, trust in politicians is at a record low. Ask the next person you meet whether they admire MPs and its 100-1 on that they’ll say no. Helena Kennedy has been receiving a respectful hearing for her proposal that we replace decision-making by MPs acting as representatives by, er, citizens acting as representatives. As if MPs weren’t even worthy of being thought citizens any more. I’ve lost count of the times I’ve heard someone argue that the solution to a given problem is to take the politicians out of it and replace them with so-called independent people.

But it is not corruption that is to blame for the decline in trust. For all that people think (wrongly) that MPs are on the take, it is not dirty tricks and financial shenanigans that have brought politics low. It is, and I realise that this is hard to take, the opposite. The signal that there is something wrong with British politics is that there is so little corruption and too few real scandals.

Corruption is the product of two things. The first is the attitude of a particular culture towards such behaviour. Fortunately, we live in a country that believes in rules and we are, by nature, a law-abiding people. I am generalising, of course, but we are, correctly, hard on those who commit even fairly minor transgressions.

But the amount of corruption depends on something else, too — the opportunity to behave corruptly. And in our country this is reduced by our monolithic political system and the centralising of all real political power on a very few people.

Let me give you an example. In Britain we had a massive scandal based on a couple of MPs being willing to accept a modest sum to ask a parliamentary question. In America John F. Kennedy became President despite accepting money from the Mafia, delivered to him by a shared mistress, and using Frank Sinatra to help to disperse it as bribes. Yes, the difference lies partly in our attitude towards such impropriety. But it is also that in America you have vastly greater number of independent political actors raising their own money and creating their own political machines. And the inevitable result of such greater freedom is that some of these people will behave improperly.

In an excellent series of articles, the political scientist Michael Pinto-Duschinsky has been warning us about increasing amounts of voter fraud. And he selects an interesting culprit (alongside the porous postal vote system). Increased allowances for local councillors has made gaining that status more valuable. The greater the range of positions of political power that are available, the more corruption you will see.

Think about the suggestions being made for dealing with the fundraising scandals in British politics. Some argue that the parties must do less and spend less, while others argue that donating money to a party should be banned and replaced with block grants from the State. In other words, the canvassed solutions reduce political activity, diversity and freedom even more. I’ve often wondered how long it will be before someone suggests having no political activity at all, just to be on the safe side.

There is, don’t get me wrong, logic behind these ideas. They recognise that corruption is an ugly by-product of freedom and diversity and seek to curtail freedom and diversity to eliminate corruption.

But there is a price to pay for such an attitude. And it is this price that leads me to say that lack of corruption is a signal that something is wrong in British politics. The price is a stultifying uniformity, a requirement that every maverick like Mitterrand be controlled entirely by the party machine, a centralisation of power on clean machines to keep out the Kennedys, a system in which the crooks are kept out by keeping out everyone. There are no independent campaigns to speak of, and few powerful offices outside Whitehall. A scandal involves someone departing from the party briefing sheet.

I am not for toleration of corruption. Not even of a stolen postage stamp. But as the police limber up to knock on the door at No 10, I hazard this: it’s not corruption that’s destroying political life, but our unwillingness to gamble on freedom.

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