"DUBLIN was where I cut my teeth as a writer but I always knew I would move on. I'm a big city boy and like operating in a big place and I was tired of running into old mistakes on the street."

It could be the opening of one of Douglas Kennedy's novels: first person narrative, punchy, pacy, laced with humour; edged with menace. But it's not. It is simply that Kennedy speaks as he writes.

Kennedy is a wanted man. The phone never stops ringing. While the ex-pat American talks New York Times bestseller list to his US agent, the Irish Times journalist explores the house, a post modern interior hidden within a Victorian shell: stainless steel fridge, sarcophagus sized sofa (papal purple), ladder style radiators. Kennedy, his wife Grace Carley from Cork, and their two small children moved in last week from a cramped flat a few miles away. Builders thump upstairs.

The radiators were the key, Kennedy explains. Like the first lines of his novels, they set the tone and got things going. Outside, it's just another villa in leafy south London. Inside, it's a New York loft.

The "classic slow climb" from free lance journalist to million dollar novelist gives Kennedy the right to revel in the trappings of success. "It's a normal family house. It's nothing spectacular and that's basically my take on it. You make a million pounds and by the time the tax man and your agent have their hands on it, it becomes half a million pounds." Which is why it's Balham, not Belgravia. And that's fine by him.

"I prefer a few nice things. I like elegant stuff and I think I have an eye for that, but I also think that's much more pleasing to the eye than ostentation."

This is a man who has learned the value of money the hard way. (The sea green kitchen units are flatpack IKEA.) In 1983, when he left his last permanent job running the Peacock Theatre in Dublin, he was living on £70 a week. Last year he earned a million. "And I do laugh at that, I mean what else can you do?" Kennedy's laugh is unexpected, like a rusty tap that splutters, then bursts into unstoppable flow.

Douglas Kennedy was born in New York City of a well to do family, and educated at Bowdoin College, territory he uses to good effect in his latest mid life crisis novel, The Big Picture, which follows the fortunes of a Wall Street lawyer and would be photographer who, after a moment of madness, finds his world turned upside down.

Unlike his protagnnist, Kennedy did not choose the corporate route. He spent a year studying at Trinity College Dublin, before returning to New York to work as a stage manager "off off Broadway". In 1978 he came back to Dublin for a two week holiday and was persuaded to stay and set up a fringe company. "A year and a half later I was still there, living an enjoyably - hand to mouth existence, when I heard that the Abbey had an opening for an administrator at their second theatre and the next thing I knew got the job."

At night back at his flat, he would write.

"It was something I had always wanted to do but I didn't express very loudly to people," he says. First came short stories, then radio plays. "Dublin being Dublin, an actor friend of mine was in RTE and showed a short story to a producer. `This would make a good play', he said, `can you adapt it?'"

Which is how, in 1980, Shakespeare On Five Dollars A Day, came about. Starring Ray McAnally, it was sold to BBC Radio 4. "So I had my first BBC sale when I was 25. It was £600, which was a fortune in those days." The wheel had slowly begun to turn. He began thinking he might be able to make a living at it.

"I kept having this idea how wonderful it would be not to have to work in an institution like the Abbey any more. It's a very nice place but it is an institution and ergo a political minefield." He left, after five years, in the summer of 1983.

Next came freelance journalism including a column for The Irish Times where he lasted a year. "It was me sounding off on something arty farty every week. It was good for about six months. Frankly, by the end of it I didn't like the column either." Around the time he parted company with this newspaper, his first stage play also flopped.

These two setbacks led to a three month trip to Egypt for a travel book, Beyond The Pyramids, eventually published in 1988. Two further travel books followed. The books are more in the style of V. S. Naipaul (with added wit and anecdote) he explains, than that other ex-pat American, Bill Bryson. "Naipaul's approach to travelling down the spine of a culture interested me a lot more as a writer. Bryson to me is a stand up artist. It's just one joke repeated 100 times."

Kennedy's first novel, The Dead Heart - which didn't even find a publisher in the States - is now a movie, and opens in Cannes this week, under the title Welcome To Woop Woop.

"MY rather dark, quirky little novel has turned into a musical," he says. He hasn't seen it but isn't worried. "Anyone who thinks when you sell your film on you'll get some authentic reproduction on celluloid is a fool. It's a different game. You just take the money and run. I wish the film well."

American rights to his second novel, The Big Picture, published in Ireland this week, were sold for $1.1 million. Film rights have already been bought by Fox for an undisclosed sum.

Late success has its advantages, Kennedy says. Too young and the tendency is to believe "the sun is shining out of your sphincter and essentially you're set for life.

"If you're 42, and you've got a couple of kids and you've been doing this for 13 years, you think `I guess I wrote a good book, and I guess I'm very very fortunate'." In The Big Picture, within the format of a thriller, Kennedy has written a powerful story of identity and emotional pain that pulls no punches. Like his new house, the shell may be familiar, but on the inside nothing is quite what you expect.

Everyone suspects, when you get that sort of money, that you've dumbed down to write it - that you've written a bonk buster or a `can you diffuse a nuclear bomb' kind of novel. So it is wonderful when it makes the bestseller list, yet at the same time resonates with people and gets critical attention.

"I feel strongly there is no reason why you can't write a big commercial book that is also grappling with serious stuff.

"This notion that literature is either art house - poetic and intense but in some sense detached from the real stuff of life or after sex I went shopping junk is just nonsense."

There's no trick to it, he says. "If you're writing a serious work of popular fiction you should try to write as well as you ever do, you shouldn't speak down."

Both The Dead Heart, set in the Australian outback, and The Big Picture have ordinary guys as their narrators. Although they are very different books, the motor of each is fear. "I'm not somebody who has done time in a home for alcoholics or had four wives and a criminal record. On that level, I've led a happily uneventful life. But I can always imagine dark situations. Everyone comes from that, don't they?"

The fear that inhabits The Big Picture is the fear of a father losing his children, although not in the obvious way. I believe very strongly that once you have kids they become the centre of your life and your life is emotionally balanced or imbalanced because of that. I can't think of anything worse than having to say goodbye to your children. This is the central dilemma of the book. And I couldn't have written it without having had children. I don't think you understand that depth of feeling. I have friends who don't have children who say they understand, but they don't. They don't have a clue.

"Fear is a very defining aspect of all of our lives. Without it, what would we be? People are always talking about how contentment is such an important goal in life. Contentment is boring. Contentment is really boring. Contentment is in a way giving up." And you, I ask. Are you content?

The big city boy looks across his designer kitchen to the playroom beyond, where the floor is an obstacle course of Lego and picture books.

"Momentarily," he says.