Eimear McBride: 'There are serious readers who want to be challenged'

Eimear McBride was in her mid-20s, living in Tottenham and working at a terrible temp job in the City, when she decided to read Ulysses. She had been trying to write for a while, and one 20-minute train journey with James Joyce changed everything. "I started reading the book, got off at Liverpool Street, and just thought: that's it. Everything I have written before is rubbish, and today is the beginning of something else."

Not long afterwards, aged 27, she wrote her novel, A Girl Is a Half-formed Thing, in six feverish months. This week, 10 years later and after a stack of rejections, it won the Baileys Women's Prize for Fiction (formerly the Orange prize), beating big, brilliant novels by established literary stars Donna Tartt, Chimamanda Ngozi Adichie and Jhumpa Lahiri.

We meet a few hours after McBride, 37, has taken to the stage, eyes shining with tears. She is being interviewed in a large side room at the Royal Festival Hall, people buzzing around, trying to keep their voices down. There is the furtive pop of a champagne cork, friends and prize judges whispering urgently, passionately, about the book; when McBride comes to the end of a short radio interview, someone's tentative whoop turns into a collective roar of approval.

The book has been described as difficult, because of its language; devoid of commas, a fractured, poetic, pre-conscious voice, pregnant with full stops and half rhymes, which McBride knew she had captured when she wrote the first lines: "For you. You'll soon. You'll give her name. In the stitches of her skin she'll wear your say." But it actually feels like language anyone could read and understand. Its subject matter is the real difficulty, the story of a young girl, struggling to deal with her older brother's illness – a brain tumour – and the abuse she experiences.

As she wrote, says McBride, disturbing themes bubbled up, unforeseen. "There's a moment where the girl is in the kitchen with her uncle, and he's about to do what he does, and she says, 'he didn't get me', or a line like that. And then the next line is, 'Oh, but he did'. And that very distinctly was me trying not to let that happen in the story, and then realising that it would … I thought, 'Oh god, don't be the Irish writer who is writing about child abuse.' I really didn't want to. But it seems I had to."

McBride had been given the gift of six months to write the book – her husband, William Galinsky, had directed a production of The Winter's Tale in Tokyo, and gave her a portion of the fee. She committed to 1,000 words a day, and "it felt like I was in this kind of death match. It involved pulling it out, pushing it out. It was not something that flowed."

Once finished, the book could not find a home. She sent it to agents and publishers, and while many were positive – no one suggested she wasn't a writer – they felt it was too much of a risk, too difficult to sell. "I knew it wasn't easy to be published," she says, "but I certainly never expected it to be this hard. I didn't feel the book was without precedent in all of literature – I had no idea it was going to be treated as a crazy book, written by a madwoman, you know?"

She turned down the idea of publishing it as a memoir – since it wasn't one – and after about five years, "I put it in a drawer and started work on my second book. I had to go through the process of accepting that I might be a failed, unpublishable writer, and would I continue if that was the case? And the answer was yes, I would, because that's who I am. But it certainly takes a toll on you, personally, to be a failure for all of your adult life."

The novel was finally published in 2013, nine years after it was first written, by Galley Beggar Press, a small, independent publisher in Norwich, where McBride, Galinsky and their two-year-old daughter now live. It was hailed with long, glowing reviews in the Times Literary Supplement, and the London Review of Books; in the Guardian, Anne Enright described McBride as a "genius". It has since been published by Faber & Faber, and has also won the Goldsmiths Prize.

Her experience suggests publishers have been underestimating readers, says McBride. "I think the publishing industry is perpetuating this myth that readers like a very passive experience, that all they want is a beach novel. I don't think that's true, and I think this book doing as well as it has is absolute proof of that. There are serious readers who want to be challenged, who want to be offered something else, who don't mind being asked to work a little bit to get there."

She hopes her success might lead to the publication of other seriously ambitious novels. "There is a readership there, they deserve to be catered to, and literature needs new blood pumped through it all the time, or it becomes stale and purposeless. It's not a museum piece. It needs to be pushed forward."

Born in Liverpool, the third of four siblings – the rest of them brothers – the family moved to Ireland when McBride was two. Her parents were both nurses, practising Catholics, who had spent time working with the criminally insane; her father continued working in Ireland, in a home for the mentally disabled, while her mother looked after the children. McBride was taught to read, aged three, by her father. "We grew up in a house with very little money, but I never asked for books that I didn't get. That was paramount."

Her parents' work made her aware from an early age, she says, "that a lot of people lived with difficult things … and that was not something that should be hidden away, or ignored." This understanding deepened when her father died of cancer when she was eight. Her mother sent her to drama classes, as an outlet for her feelings, and she developed an ambition to act.

At 17 she moved to London for a three-year course at the Drama Centre – sometimes wryly known as the Trauma Centre. "I was very interested in The Method," she says, "and it's a method school, Stanislavsky training, and that's what I really wanted to pursue. It was very, very intense, 11 hours a day, and there were all these crazy exercises to try and break yourself down, to dig into the darkness within, and I loved it, of course."

They read from the ancient Greeks through to Tennessee Williams, and the sum of that training is in the voice of her novel. "A lot of the book is like a description of what is going on in a method actor's head on stage. It's about trying to draw in all these disparate experiences: so what is being said, and also how a person is reacting and feeling, what they're feeling about the feeling, what they're thinking. What other thoughts are going through their heads, and their gut reactions, and physical sensations. You know, if you're itchy or need the loo when you're saying something, that also affects how it's said, and received."

Acting had seemed like a protection, a place where she could express and explore difficult emotions, but when her brother Donagh died of a brain tumour in his late 20s, not long after she finished her training, McBride realised there was no protection. "I stopped wanting to be an actress," she says. "I had felt as though the bad thing that would happen in my life, had happened, and when my brother died I realised that anything can happen at any time, and there was nothing you could do about it."

A Girl Is A Half-Formed Thing is dedicated to Donagh, and features obvious echoes of his illness, but she says she gets quite upset, "when people say, 'this is like your brother'. I think, well, this is really not about my brother, this is not his life, and I am not that girl."

McBride's second novel is almost finished, and she says she tries to be fearless in her writing, to move beyond her natural boundaries. "I certainly try to go in with as little self-censorship as possible. I try to write from a part of myself that is not concerned with how it will be received, what people think about what I should be writing, and that's very important. It can be disturbing, because it's something that's then outside of your control, and you end up writing things you don't want to write, and discussing things you don't want to discuss, that personally you don't feel comfortable examining.

"But if you are not uncomfortable as a writer, then you are not doing your job. Your job is not to feel great about everything. Your job is to look at what is difficult and to try and understand it in some small way." With A Girl is a Half-Formed Thing, McBride has done that. I suspect in years to come – maybe even a century from now – an aspiring writer will read it on their way to a drudging, unhappy job, and feel that everything about their world has changed.