It sounds an idyllic lifestyle — and it is. "The irony is I grew up in a small town and couldn't wait to get away," says the 41-year-old writer, "and yet I ended up living a similar kind of life. When you have children, that's how you want to live: in a community where everything you need is on hand and everybody knows you."

Her novels are largely set in the fictitious town of Ballyfergus, loosely based on the Ulster home town of her childhood. "Northern Ireland is very important to me and I'd find it very hard to write about anywhere else. Ballyfergus isn't Larne — I've changed it. But now I've created this place, it's very easy to go back there and write stories and situations around it."

Another fiction is Erin's name. Named Patricia, after her mother, Patricia Kay (with no 'e'), her actual name clashed with that of an established American crime writer. She opted instead for the nom de plume 'Erin' — what she would have chosen for a daughter, if she'd had one.

"But when I ran 'Erin Kay' in an Internet search engine, it linked to porn sites! So I had to add a final 'e' to the surname. I've got used to Erin Kaye now — I'm very comfortable with it. I'm happy for people to know me as Erin."

Born the fourth of five siblings to a Polish-American father and an Anglo-Irish mother, her favourite subject at school was English, which she took to grade A at A-level.

"We didn't have a TV in the house until I was well into primary school. I remember in P6 my teacher didn't believe that I had read Dickens' Great Expectations — but I had."

Somehow, instead of opting for English literature, she got diverted into a geography degree at the University of Ulster and, straight after graduating, married Mervyn.

Together they moved to Aberdeen where Erin joined a Scottish bank. "I thought I wanted a sensible, well-paid career."

Ten years later she had risen to the rank of associate director and board member but the crippling long-hours culture was leaving little time to nurture a desire she had always harboured — to write. As for fitting a family around the job, she felt she might as well forget it.

"The bank had been a very good career for me. I was very well regarded and well paid. But I became totally disillusioned. One night my husband and I came in from work at 11pm and just looked at each other. Something had to change."

In 1997, she threw caution to the wind, handed in her notice, closed the book on one flourishing career, to start straight away on a fresh page with another.

"It was the craziest, most foolhardy thing I've ever done," she recalls. She might, occasionally, regret the lost pay slip but, really, she has never looked back.

"I can't remember if I started my first book before I left the bank. I don't think I did. But as soon as my time was my own I got straight into it. I'd given up my salary, we'd cut back, downsized the car, stopped going on holidays and so on. From the start I treated writing as a proper job — and lived in hope of my big break."

She got that break — but it was 2003 before her first novel, Mothers and Daughters, was published by Poolbeg, followed by Second Chances, Choices and Closer to Home.

A fifth and latest novel, My Husband's Lover, looks set to strengthen her fan base. Erin's writing has been compared to Cathy Kelly and Maeve Binchy but, really, her work has its own place.

A good novel must be entertaining, she believes, and yet have something to say.

Hers "tend to be a bit dark", she feels. "I like to think people get something from my writing and maybe learn something." Readers also, just love a good story and Erin delivers here.

"I find Larne an ongoing source of inspiration for my books, along with my mother, who was a health visitor and local councillor, and is full of great stories. Of course, I'd never reproduce a story directly or use peoples' names — everything I write is fiction — but everything I see and hear gives me nuggets of ideas.

"For instance, recently I was coming up on the train from Dublin, sitting near three 30-something women. I was pretending to read my book, while ear-wigging in on their conversation about boyfriends, clothes and work. I do that all the time. And I read women's magazines like Red and Marie Claire and the likes of the Sunday Times Magazine for topical human issues."

As well as producing five books in the years since she jacked in the bank job — a sixth is already under way — Erin has produced two much-loved sons, Ryan and Liam, the family she feared that continuing with a corporate career would rule out.

Life is good. But there's been a shadow over their happiness. The younger boy, Liam, just turned six and finishing his first year at primary school, has Langerhan's Cell Histiocytosis (LCH), a serious and very rare cancer-like disorder, which, like leukaemia, originates in the bone marrow and spreads through the blood stream. Fewer than 100 cases (mostly children) are diagnosed in the UK each year.

While it acts like cancer, LCH is thought to be some kind of auto-immune disorder which can, in time, spontaneously cure itself. Treatment depends on how the condition develops and careful monitoring is needed.

"I don't accept that anything's going to happen to Liam. I don't go there at all," his mum says, simply. "We've had a year without any recurrence of these tumours and the longer he goes without recurrence, the better the news is. A year is fantastic. We're very positive, while being hypersensitive to things and watching him very carefully."

As is, blessedly, often the way with young children, Liam appears very matter-of-fact about the whole business and just gets on with the things that really matter, like his friends and toys and pet dog.

"If we ask Liam about his sore eye, he can't remember which eye it was. Whether he pretends he doesn't remember or really doesn't remember, I don't know. We all try to be matter of fact about it and never show upset in front of Liam."

In what passes for spare time, as a busy working mum, Erin is involved in everything from charity fundraising to mini-triathlons but is, she says, at heart a solitary soul — just as well, since that's what the life of a writer essentially is. She comes across as a bubbly, upbeat conversationalist but claims to be a born pessimist who has learned to switch on to "party mood" at the click of her fingers.

"I'm fine in conversation with people but I also like being on my own. Writing is solitary. When I work I speak to nobody, it's head down and get on with it, day after day. It doesn't really bother me, though it might drive a lot of people nutty. But you also have to be able to go out into society and get to know people — that's your material."

Her writing is a creative process but a job of work. "My approach to writing is very professional, very driven. I write solidly when the boys are at school — but, really, that's no time at all and it flies."

The latest book took three months solid focus to complete. "I was working at 3am and all day at weekends. My husband took the kids away at half term to see family in Ireland. Working solidly at a stretch like that I can get a lot done — 60 pages in a couple of days, which would ordinarily take me weeks to do."

My Husband's Lover — the title alone just makes you want to know more — is being heavily promoted at Waterstone's, and Easons. "It shifts a lot of copies and people start to look out for you. What do I feel when I see the finished book on the shelves? I feel relieved because it's such a struggle to get it there, when you've got children and a busy life doing other things. "

When will she feel she has properly made it as a writer? Perhaps, she muses, when she is a UK household name. "I'd need to be earning an awful lot of money from it before I would be happy," she says frankly. "My object was never simply to see my first book published — rather it was to establish myself as a writer and to earn a living from it."

With such due diligence to the bottom line, it seems you can take the girl out of the corporate world but, perhaps, never entirely take the corporate world out of the girl.

You can find out more about Erin Kaye and her books on www.erinkaye.com.