Many people are surprised when they learn I was once in a pop group. For some reason they find it hard to imagine that anyone could make the switch from playing guitar in the Thompson Twins in 1982 to writing serious books two decades later. But actually I'm far from special: isn't the progression from guitarist in a college band to prime minister a greater leap?

In the earliest days of my writing career, I could not decide whether I should or should not mention my musical past to prospective agents and publishers. Friends assured me that if they had been in a famous band they wouldn't hide the fact. But I quickly learned that many in the publishing world think pop music began and ended with the Beatles, so the reaction I received was mixed. Of those who had heard of the Thompson Twins, some saw the publicity potential, while others ran a mile. One publisher, confronted with a proposal for a biography of Stephen Hawking from a former pop musician, told my agent she was utterly insane to be representing me.

The irony is that I was writing before I had any success as a musician. In my final year at university I spent every evening pouring my life's blood into an Expressionist novel I sincerely believed had Booker potential. It was only after graduating that I found myself in a professional band, touring America. This was, of course, the most exciting thing that had ever happened to me, but even on the tour bus I had a notebook and pen (oh, for a laptop in 1982), scribbling away at ideas for future novels. When, inevitably, my pop music career vaporised, it felt perfectly natural to turn back to my first love.

I still compose and record music, while my literary subjects have ranged from Mozart to quantum mechanics. I decided long ago that a wide range of interests is a useful resource for a biographer, though some subjects have proven easier than others. It must have been some impish trainee meddler at Fate Central who brought me to my latest subject, JRR Tolkien, for the creator of The Lord of the Rings was quintessentially single-focused, devoting his life to the creation of Middle Earth. Initially this worried me so much that I almost turned down the project; but on reflection I hoped that the personality clash between biographer and subject would make for a fresh perspective. Vive la difference.

· Tolkien: A Biography is published by Abacus. See www.michaelwhite.com.au.