"But she married me, so that was all right," says the author of the best-selling The Rosie Project and The Rosie Effect.

Twenty-odd years later this fellow got in touch, he had just broken up with his wife, and Buist suggested he come and stay for a few days.

"I said, 'Absolutely not'," Simsion says, "but as it turned out he was a lovely guy, we got on extremely well.

"But afterwards I thought what if it had turned out differently? What if it had rekindled their old relationship?"

And that's where the best stories come from, Simsion says, something happens in real life and you ask yourself "What if?"

And the what if here, turned into The Best of Adam Sharp, Simsion's latest book.

As it turns out, Simsion and Buist have stayed in touch with this man, have caught up a few times; Simsion even used him as an adviser on Adam Sharp.

"You travel a long way away from the original characters who inspire a story but Adam Sharp does have a little bit of this guy in him.

"But this guy doesn't play the piano, he is from Manchester and he does work in IT but there's a certain amount of me in Adam and there's a certain amount of a good friend who plays the piano in him, too."

Men have played an integral part in Simsion's books. Don Tillman quickly became a character of the ages. His fears and foibles were our own, we cherished his differences. For as much as he frustrated us, we cheered for him, championed him.

"I've always been very concerned about the idea that the men in my books have to be authentic," Simsion says.

"I don't want them to be cardboard cut-outs."

Part of this comes from the idea that Simsion wants men to read his books.

"It is the bane of my life, it is such a challenge and it's one I want to be able to rise to," he says.

"I'm constantly getting feedback from my editors, particularly overseas, saying 'our female readers', constantly assuming that the market for books about relationships will be women, and not very sophisticated women at that … we're talking about some undefined woman who likes to read about romantic escapism.

"The trouble is I say, 'What about men?' and they say 'Men don't read fiction about relationships'.

"And if I change my book to suit that archetypal woman then men won't certainly want to read it.

"It becomes a vicious cycle, if we write for the supposed market and an intelligent man does pick it up and try to read it he'll say this is not authentic about men."

Simsion admits that most men will end up reading his books because their partner has given it to them and said "read this, you'll love it".

"That's how Bill Gates got to read it, because his wife Melinda read it through a book club and said, 'Bill, you have to read this book'. He didn't walk into a bookshop and say, 'I'm going to buy a book about a relationship.'"

The Best of Adam Sharp, by Graeme Simsion. Text Publishing. $29.99.

Graeme Simsion will be in conversation at an ANU/Canberra Times literary event on Monday, September 19 from 6.30pm. Free. Manning Clark Centre, ANU.