Second Thoughts: Choosing to play at Wembley: Robert Harris recalls the uneven road that led to Fatherland (Arrow, pounds 4.99)

I HAD the idea for Fatherland in 1987, but I had no chance to develop it until the beginning of 1989, when I became a columnist for the Sunday Times. I no longer had to attend an office. I had half the week clear. If I didn't write a novel now, I told myself, I never would.

I had always loved the storytelling part of journalism and fiction seemed a logical next step. Working for the BBC had taught me the importance of structure. People watching a television film cannot skip back a few paragraphs as they can with print: they must understand everything at every point. I know literary bores tend to castigate television for corrupting young writers, but the medium does a lot to foster clarity and economy.

I spent the whole of 1989 researching Fatherland, then wrote the first 15,000 words, only to find myself with no real idea who my characters were or what was to happen to them. I abandoned the manuscript in despair and wrote a biography of Bernard Ingham instead.

Perhaps this gave me the insight into a totalitarian regime I had been lacking. At any rate, I did what I should have done at the outset: structured the story through to the end. I did not stick to my plan - on one grim day, I remember, I had to discard almost 20,000 words - but I had a path to follow and six months later I had finished.

There are now 2.5 million copies of Fatherland in print around the world. I did not set out deliberately to write a bestseller although, in retrospect, it was obviously implicit in my approach. I see all forms of writing - print and television journalism, non-fiction books and novels alike - as a kind of public speaking, the aim of which is to reach as many people as possible. To me, the prospect of packing Wembley Stadium is infinitely more exciting than talking to a half-empty hall, even if it is at the ICA. This is considered rather a shocking and vulgar thing for a writer to admit, yet, curiously, nobody would criticise a musician for expressing such an ambition.

My second novel will be more severely judged. Critics who were indulgent of my faults this time will, quite properly, be more demanding next. So be it. I console myself with the thought that I never expected any of this, that I had a lot of fun, and that at least I played Wembley - once.