Ghostwriters have been around since medieval times when only a handful of the population could write. Everybody else had to hire scribes.

Nowadays I'd say 40-50% of non-fiction titles in any given bookshop are ghostwritten. Anyone who has expertise to pass on, but who doesn't have time to sit down and write a book will hire a ghostwriter. That ranges from businessmen to footballers and actors.

Say I wanted to write a book about hairdressing. I know nothing about it so I'd have to interview hundreds of hairdressers and do months of research, and then I'd go to a publisher and pitch my book. However, if you ghostwrite the book with someone who has the authority and experience of being a hairdresser themselves then it won't take as long and it's easier to sell. They have the knowledge, you have the writing skills.

I did an autobiography for Big Brother winner Pete Bennett. It was high-pressure because everyone was rushing in to capitalise quickly when he came out of the house. The publishers hurled money at him and we were locked into a hotel suite in Covent Garden. We spent a week talking and recording his story. After that Pete was able to go off and do photo spreads and interviews while I wrote the book.

In a Guardian interview they asked him 'what's it like to be an author?' He said 'I'm not really. This posh geezer came round with a tape recorder.' That kind of honesty means it's harder for people to be snobbish about ghostwriting. These days people like Jordan and David Beckham are very open about the fact that they don't write the books. They've done the profession a big favour.

Having said that, there will always be snobbery around writing. People turn their noses up at J.K Rowling for not being the next Proust. When did you last buy a copy of Proust?

I started ghostwriting when I was a freelance writer. I was making money any way I could. I interviewed a businessman for an article and he told me he'd been commissioned to produce three books on business management. He didn't have time to write them, so he asked if I'd help. We did a lot of interviews, he invited me to his seminars and gave me access to his documents, and then I went off and wrote the books for him. Being a freelance writer can be quite hand to mouth. Ghostwriting is just an extra source of work.

There are experts everywhere who don't have time to write down their expertise. That's a good place to start. Think about people you know. Once you've got some experience you can also approach magazines and publishers. Don't expect to get a best seller straight away. All literary agents are in contact with a few ghosts. We're not really a species on our own; most writers ghost at some stage in their career.

People often ask if I'd like to write something under my own name, but being a ghostwriter doesn't stop you doing that. It's just an extra source of income. I've written my own novels, but it's hard to make a living from fiction.

If you're a writer there's a huge temptation to sit in your room and not engage with the world, but that doesn't give you anything to write about. I've ghosted books for celebrities, people who've been abused in childhood, Chinese billionaires and Nigerian industrialists, people who I would never normally get to meet. It's taken me to places I'd never normally go. It all helps when I write my own fiction. I have a greater understanding of how life ticks.

Andrew Crofts was talking to Katie Jackson.