My Greatest Mistake: 'It was absolute nonsense, no truth in it whatsoever'

I've made so many mistakes it's embarrassing. Some can still make me wake up in the night, sweating.

In the mid-Seventies, I was a very eager, enthusiastic young political correspondent for The Guardian. We got hold of a secret document from Tory central office. It appeared to show that the home secretary, William Whitelaw, was going to introduce nationality quotas for immigrants – a very controversial plan. It was the splash in the paper at the beginning of one of the Tory spring conferences, which Whitelaw was addressing. What a wonderful scoop! I went to the conference with a spring in my step, expecting plaudits from all my colleagues. But Whitelaw absolutely rubbished the piece: it was absolute nonsense, no truth in it whatsoever, he couldn't imagine where it had come from. I had that awful feeling when your ears glow and your stomach turns over. It was ghastly. I think what happened was that it was a genuine document but had been rejected. Because it was presented as policy, I thought it was policy and failed to make the crucial check. Anyway, I offered my resignation to the paper. To my intense relief they turned it down.

Other times I have made total misjudgements. In about 1982, I wrote one of the first pieces I'd seen about personal computers for The Observer magazine. I said only a few people would ever have them.

The whole art of journalism is to make it sound as if you know what you are talking about, even when you are bullshitting. As soon as you have been proved wrong, you simply sail on to the next thing and hope that not too many people remember.