Young author's world turns upside down after making the prestigious shortlist for the Man Booker Prize

The smartest young writer anyone is ever likely to have coffee with is cosily wrapped in a knitted jumper against the spring freshness. It is the morning after the plane arrived from Britain via Sydney and delivered her from a stream of interviews. It is the week after the week in which her life changed. Where she once was Ellie Catton, writer of enormous potential, she is now Eleanor Catton, Man Booker Prize shortlisted author. And on Tuesday, she turns just 28.

Having woken in her own bed for the first time in eons, she pushed exhaustion aside and agreed to one more interview, a kind of integration home after a circuit of British book festivals that accelerated into that mad whirl of appointments when her novel, The Luminaries, was named among six in the running for the best-known prize for fiction, never mind the £50,000 ($96,000) prize that goes to the winner.

Catton is the third New Zealander to be shortlisted, after Keri Hulme, who won in 1985, and Lloyd Jones. If she wins, she will be the youngest to do so. Heady stuff. Fortunately, Jones has provided brilliant counsel. "He wrote me a couple of really lovely emails. He told me to go down to Ladbrokes and take a bet on myself, which I thought was really awesome advice." The bookies have her as third-favourite.

After our interview we learned that Catton had arrived back to news that an ailing close relative had died, and yet went ahead with the appointment, which I think says something about her commitment. First thing you notice is her shining, attentive blue eyes. She is grounded, calm, serious, ageless and ferociously intelligent. Life has flipped from the norm of entire days spent alone writing, to being the subject of great curiosity. She's learning about that as she goes, she says, and admits she is less comfortable about interviews like this one in which she's asked about herself as much as her work. Suddenly, people expect her to have answers for all sorts of things, she recently told a British interviewer. She's been asked what her favourite word is. "I was like, 'I don't know'." Or, how her life has changed, "and I feel, 'Well, I don't really want to tell you'. It's not there for you to see."


So long anonymity. In all the fuss that's come of the Booker list, she says, "I can feel the public side of my life and the private side of my life sort of drifting away from one another." She would talk to journalists as though they were her friends, get "too garrulous and they would, of course, end up printing what I was saying". A demarcation is emerging between Ellie, as she is to friends, and the author, Eleanor.

So long, the unguarded remark? "You don't really know how to handle it until you mess up," she laughs. In a happy, chatty interview with the Guardian, she said there was no "reviewing culture in New Zealand". That hit home. She was, she says, trying to make the point that being in the rich literary culture of London was like paradise to her. The next day on Twitter, there was "a cacophony of outrage".

At risk of ruffling feathers, she answers my question about whether she's noticed a difference in how her book is being received here compared to in the United Kingdom. "It's been interesting. I think all of the reviews I've had that have been big profile reviews from New Zealanders have been very cold, and the reviews I have had from the UK so far have been very warm. Even when the reviewers are talking about what they don't like about the book, they will say, 'there's still something exciting going on here', whereas I feel like the New Zealand ones have been more concerned with devaluing the book." Meaner? "Definitely meaner."

A review by Aucklander CK Stead, a demanding critic, in the London Financial Times, appeared under the barbed heading "All that glistens". "It's an extremely shitty headline," says Catton. Stead's review of the book that is set in gold-rush Hokitika in 1866 notes its cool tone, clear telling, exceptional detail and acknowledges "enormous talent" but concludes that, for him, ingenuity outrun admiration and became tedious.

The pattern, though muted, was there too, Catton says, with the first of her two novels, The Rehearsal, for which, at 22, she was the youngest-ever fiction finalist in the Montana Book Awards and carried off the prize for best first book. "The reviews in New Zealand weren't as wholehearted. You get the sense that praise comes through gritted teeth."

The Booker judges disagree, naming The Luminaries among the top six of the 151 novels entered and describing it as a New Zealand Twin Peaks. "It's just so nice. The shortlist is really the end of the road. It doesn't really matter who wins the prize." Her London agent, she says, summed up for her the fork in the road she has arrived at. Either she doesn't win the prize, in which case she has had a wonderful time and can go back to her own life and be very happy with her sales. Or she wins and, while that is fantastic, she is going to have an absolutely ghastly life for the next three years going on tour and losing touch with her normal existence.

Catton was in Dublin when she was told she'd made the shortlist and promptly disgraced herself in the grand, glorious, buttoned-down Trinity College library, with its ladders leaning against walls lined with ancient and rare tomes such as the Book of Kells from the 1660s, when the trill of her cellphone sliced the silence. It was her publicist. "I had this horrible ring tone. It is officially the most embarrassed I've ever been in a library, and this the library of libraries."

A kind of relaxed fatalism had since settled upon her. "I feel quite differently about the eventual outcome of the prize than I did about the shortlist. I was quite anxious about the shortlist but now that it has come out I feel very Zen about the actual prize." There is, though, the fraught business of needing to buy a frock for the posh announcement do in London's Guildhall on October 15, covered live by the BBC and at which the winner is required to deliver not just a thank you speech but something learned and wise about the state of fiction. "That makes me very nauseous," says Catton, who much prefers to think about the leather-bound edition of their book each finalist is presented with. "I'm so absurdly excited about this; I think more excited about this edition of the book than anything else."

Catton knocked out her first novel, a three-page job, at age 5 and can't recall wanting to be anything other than a writer. It's "crucial" to her to use fiction as a way of being in conversation with herself, of exploring mysteries such as "to what extent does self knowledge act as a force for good in our lives", one of the questions that lurks within The Luminaries.

An advocate of and product of creative writing courses, she says she broke basic rules by starting with theme and structure. "One of the earliest ideas, once I knew I wanted to bring in the stars in some way, was this idea that the story would involve 12 men, each of whom had this kind of peripheral relationship to a supposed murder and that these 12 men would be the 12 signs of the zodiac. I started with these big-picture themes and worked my way down to the individual." Virgo, notoriously idealistic and hard-working, is thus a Chinese gold prospector also involved in an underground goldsmithing trade; Leo, lover of games and pleasure, is a whoremonger. Catton says she didn't fully appreciate the stress of creating a book that could be read as a straight-forward plot novel but be equally propelled by its astrological structure. When she stopped, there was 832 pages. Her book is the physical heavyweight of the shortlist.

"I was happy with the way that it had tailed off. I didn't have any loose ends, I didn't have any mysteries except for the ones I felt in control of." She sent the last 100 pages off to her publishers in the UK late one night in January, about two years overdue and promptly poured a celebratory glass of wine. "The next morning I woke up and I felt lighter than I had ever felt in my entire life. All those cliches about a burden lifted were so literally true."

She had lived with it for five years, been writing it for three years, having begun in Iowa City where she attended a writers' workshop. Along with the beginnings of her epic, she returned with a partner, Steve Toussaint, from Chicago. "He did poetry and I did fiction. We were what they called a cross-genre relationship at Iowa." They live in Mt Eden and Toussaint is her sounding board. Each evening after dinner, she would read him the one or two thousands words she had produced that day. "He'd just say, 'kept going' if it was all right, or," she smiles, "we'd have an argument about it." She's a tough cookie from a bold family. Born in Ontario, she arrived in New Zealand aged 6, the youngest of three siblings, with a university philosophy lecturer father and a librarian mother. Growing up, there was no television in the Catton home and, for a while, no car.

"Our parents were really great at leaving us alone; parenting by neglect sort of thing," she laughs. "We didn't have packaged fun put in front of us." After school she would write stories on the computer in her father's university office until it was time to bike home together.

Her dad recently quit his job and is now an undergraduate engineering student at Canterbury University. He'll graduate about the time of his 60th birthday, which delights Catton. "It's so admirable. It's very brave going from a position of authority to one where you are an apprentice." Neither is she a shrinking violet. When she made what might have been her first shortlist one of several candidates for head girl of Burnside High she demanded to know why only she was not granted an interview. Told, she says, that the school did not approve of her choice of boyfriend, she chose to depart for university. A few years later, The Rehearsal, her book about the aftermath of a teacher's affair with a pupil, was published. Not that such a thing occurred at her old school as far as she knew. Then again, she's been told that the school's library doesn't hold the book so who knows?

Being a Booker shortlisted novelist will ensure the sales success of her new book and mean that financially she is "fine" even though, as she quips, she is supporting a poet. Whether success might dull her creative edge has occurred to her.

"You can tell when a writer moves out of a place of struggle and into a place of comfort, and it's always a bad thing. And it doesn't have to be financial comfort. The risk is you stop being so alive to the nuances of human behaviour. That's the nice thing about living in New Zealand - you can come back home and turn your back on all the silliness."