All Mansell knows is that life has been more comfortable since she quit her career as an electro-encephalographic nurse at Burden Neurological Hospital in the 1980s.

'I was working in the hospital for 18 years testing people's brains. It was all physics, technology, biology and chemistry. I never imagined doing that in the first place,' she says at the Sheraton on the Park Hotel in Sydney.

'I was thinking: could I write songs? I always think it's fantastic that you can write a three-minute song and it can change your life and everybody can get to know it. Like, George Michael wrote Last Christmas while watching a football programme on TV. Just that song on its own would set you up for life.

'But I can't sing in tune and I can't write music and I can't play a musical instrument. Then I read this article about romance writers and I thought I could have a go at doing that,' she recalls.

'It was a real light-bulb moment. The article was about women who'd had their lives transformed by becoming best-selling authors. I'd always thought working for the National Health Service, you know, you're not going to make much money ... But I always thought there must be some way to make money.

'I know that's not what you're supposed to do as a writer. You're supposed to do it because you love it,' she says.

Mansell's biggest challenge in a novel isn't the soundness of the story, the prose, the credibility of the narrative voice or the characters. It's the hook, usually a dilemma, that arrives within the first chapter or two and gives every character something to talk about for the remaining 350 pages, all of which are laid out with plenty of friendly, undemanding white space.

In novel 19, An Offer You Can't Refuse, released this year, we know by page 15 that Lola and her boyfriend, Dougie, can't be torn apart. Even when Dougie's wealthy mother offers the spunky working-class girl #10,000 to walk away from the relationship and preserve his upper-class credentials, 17-year-old Lola refuses, knowing that she and Dougie are meant to be together forever.

But then she stumbles on her loving stepdad, Alex, packing his bags and preparing to flee their home to protect Lola and her mum from the shame of his gambling debts. 'Unbelievable though it seemed,' Alex had been 'sucked in' by some new poker-playing friends and was 'in over his head'.

Lola is forced to take the money from Dougie's mum, leave him crushed, save Alex and flee to Majorca, hoping she can forget her childhood sweetheart.

A decade later she's back, working in a bookshop. Gorgeous Alex is dead, we're told in a two-line flashback, and Lola has promised him that she will never reveal what she did with the money. But in what they call a bizarre twist, she has inadvertently struck up a friendship with the sister of Dougie, who loathes Lola because he thinks she took the money for a tacky holiday.

How can she win back Dougie without tarnishing Alex's name by revealing his mistake?

'I always have the TV on when I'm working,' says Mansell. 'I don't find it distracting. It's relaxing and it helps, and I can often steal ideas from it. I start waiting for the sparky idea that will set you off. It's a nervous time but you know something will come.

'I take the kids to school and then I sit down and start writing. I could write faster - 1,000 words a day and I'm happy. Less than that and I'm a bit miserable.

'I tend to start an exciting new book quite fast, about 2,000 words a day. It slows down when you've introduced everybody. Then at the end you're cycling down hill at 2,000 words a day because you know exactly what's going to happen. It's more difficult in the great, big, long stretch in the middle when you have to keep it fresh and exciting.'

Mansell has already submitted the manuscript for book 20, and is well into 21. She has no qualms about leaving Britain for a book tour in the middle of writing a novel. It will still be there when she returns.

It's a good chance to check she had the geography right in the chapters of book 19 that take place in Australia. She's pretty sure the internet research she conducted while writing An Offer You Can't Refuse correctly showed her character could see the Opera House from a taxi on the way to the airport. Mansell's a bit more careful since one of her novels had a character driving around Rome's Trevi Fountain, which is impossible.

Not much else stops Mansell from writing. Many authors would have dissolved into a puddle of tepid ooze if the manuscript for their first novel vanished. Mansell just wrote another one.

A workmate of her ex-husband had offered to type the handwritten manuscript for her. 'I gave her my only copy and I never saw it again,' she says. 'I kept asking how she was getting on with it, and my ex-husband would say, 'Oh, she's enjoying it. She's getting on.' It was one of those weird situations. The longer it went on, the more I realised I was never going to see it again.

'So maybe it's out there somewhere, published under another name. It was horrific. I sort of pin all my hopes on the idea that because it was the first book it was rubbish. Now, if I'm going away I photocopy what I've written and leave one copy in my house and one copy in my mother-in-law's, in case a house burns down.'

As her book tally grew, Mansell became sick of people pointing out that romantic comedies ended predictably. So she killed Kit, her central character in book 11, Mixed Doubles. An invitation for lunch with the publisher arrived shortly after she handed in the funeral scene. Jill, the pleasant girl from Hachette Livre, said to her, for every person who says, 'Oh, it's so predictable', 10,000 more will be outraged when they don't have the right ending. Kit came back to life and Mansell has played straight ever since.

Contentment is the only way out of a romantic comedy, she says, even though her favourite book, Helene Hanff's 84 Charing Cross Road, a direct precursor of her fiction, refuses to deliver a happy ending.

When I suggest the ending to book 19 is predictable yet smoothly literary, Mansell seems perturbed. Dougie and Lola inevitably resume relations, I say, but she keeps Alex's secret after Dougie decides he has no need to know why she took his mother's money to dump him. He loves and knows her well enough to believe she must have had a good reason. Neat, even clever.

'I had no idea,' Mansell shrugs. 'I knew she wasn't going to tell him. The whole point of the book was that she couldn't tell him.'

Her publisher has learned to read Mansell's manuscripts quickly and go back to her with praise. It's not that she's the neurotic artist. More a case of so sick of writing she's convinced her career is over. 'By the time you finish a book you've been working for a year, you think it's boring. If you read a book and took a year over it you'd be bored.'

This soon mutates into a terror of never having another book idea, of losing the scent of the money, and before long Mansell is back in front of the TV with her notepad.

'I start off by organising a few characters. I choose my names from a baby-names book. The jobs come from the Yellow Pages, and then I just wait for a really brilliant starting-off idea.

'After that it's a question of: what happens now? OK, that happened, so how are they going to react to that? I sort of make it up as I go along. You further your plot as you go along, and you work it all out as you're going along. You're the author; you can make anything happen. It just has to be believable in a slightly larger-than-life way.'

Writer's notes

Name: Jill Mansell

Lives: Bristol, England, with her partner and two children

Latest book: An Offer You Can't Refuse (Headline Review, 2008)

Other works: one of the top 20 most commercially successful authors in Britain, with sales of more than 3 million from 19 books, including Fast Friends (1991), Solo (1992), Sheer Mischief (1994), Two's Company (1996), Perfect Timing (1997), Head Over Heels (1998), Good at Games (2000), Nadia Knows Best (2002) and Making Your Mind Up (2006).

Other jobs: neurological nurse

Next project: one novel completed for release next year and another in its advanced stages.

What the papers say: 'This frothy romance will give any girl the giggles and there's enough wit to keep you turning the pages.' - The Sun on Open House (1995)