I ALMOST made it. One more step and I would have been out the door. I had my hand on the handle. But I had to face it, I’d been caught. Don Macintyre of The Independent had asked me a question and was looking at me expectantly. I turned around and tried to give him an answer.

We were in the press conference room at Conservative Central Office during the 1997 general election campaign and it was the day after the coronation of the king of all the fiascos.

For months the Tory party had barely held the line on its “wait and see” policy towards the euro. Hundreds of parliamentary candidates had disavowed it, but as yet no members of the Government. Then, late one evening, the news filtered through to officials at Central Office, of which I was one, that two junior ministers had used their election addresses to announce that they were opposed to the euro altogether.

What should the Prime Minister do? Sack two ministers for saying what most Tories thought? Or let them stay in the Government and end up looking weak? The answer was the only one a professional politician could give — it was decided not to answer the question.

Journalists were to be told that the election material had been misunderstood, that the ministers had thought they were agreeing with the policy, but had phrased their leaflets infelicitously. Obviously, this was ridiculous.

“If we’re going to say that, I’m not going to the press conference,” I announced with as much pomposity as I could manage (a lot). But a friend explained that if I didn’t go I would risk “Man-you’ve-never-heard-of-and-whose-name-you-can’t-pronounce snubs Major” headlines. So I wound up my “Darlings, I can’t go on” act and proceeded to the press room.

It went fine at first. I repeated the line to one journalist after another, moving so quickly that no one could ask me anything about it. Then, as I was making good my escape, Macintyre stopped me. “There’s one thing I don’t quite understand,” he said. “You say they should remain in the Government because they thought what they wrote in their leaflets was consistent with Government policy. But doesn’t that just mean they’re too stupid to remain in the Government?” I smiled weakly, mumbled something like “Oh Don, you wag” and left.

The lengths politicians will go to in order to maintain the fiction that they agree with each other are extraordinary. There is an unwritten political rule, with which the media collaborates, that almost anything is better than acknowledging a difference of opinion in public. Looking foolish, being intellectually dishonest, suppressing your opinions, anything.

Although the papers have been full of stories about Boris Johnson’s adultery, such things don’t automatically produce resignations. No, what did for Boris was the far worse political sin of trying to be a frontbench spokesman while having and expressing the occasional opinion of his own. You might think Michael Howard should have overlooked that. But this is unrealistic. He couldn’t possibly, you see, because pretending that he and Boris concur on absolutely everything is a fundamental law of politics.

And what a silly law it is.

Politicians join parties because they agree with the broad sweep of policy and philosophy. They cannot be expected to share the same view with hundreds of other colleagues on every last detail of policy. If you force them to pretend that they do, by threatening sensational headlines every time they depart from the script, then you risk creating dull machine politics in which careful words are used to cover up gaping holes.

The public must choose between open and honest discourse on the one hand and illusory unity on the other.

In his fascinating book The Wisdom of Crowds, James Surowiecki argues that allowing diversity of opinion is essential if groups are to make sensible decisions. The way political parties make their minds up is, according to his theory, the worst possible way to reach a conclusion. A few people at the top choose a course of action and everyone else follows. Those who disagree are under huge pressure to keep their mouths shut.