Robyn Cadwallader first came across the concept of an anchoress, the word used to describe such women, when she was already mired in thirteenth-

"I came across this word 'anchoress', wondered what it was, started to read a bit more and was absolutely horrified, fascinated, really thought it was just a terrible, terrible thing," she says. "I just kept reading and in a way, it wasn't essential to the thesis, but I was so fascinated by it that I just kept reading."

As she read, her thoughts shifted, and she began pondering what it would take for a woman – a young woman, particularly – to choose this life, even in an era in which women were entirely constrained by their culture. What drove her there? What in her life was she running from, and what did she expect would happen to her mind and body once she was enclosed?

Cadwallader could see a story forming in her mind, although it would be years before it was fully realised. A young woman, barely out of her teens, facing her new reality, with the ghosts of previous anchoresses still lingering in her gloomy cell – it was a narrative that was compelling on several levels.

And when the book was finally finished, several publishers agreed; The Anchoress, out this month, is being published by HarperCollins here, Faber & Faber in Britain, Farrer, Straus and Giroux in the US and Gallimard in France.Paradoxically, says Cadwallader, all three English-language publishers have told her it's the very strangeness of the premise – the distance in both time and situation – that enhances its relevance for today's readers, especially women.

"That's the thing that they kept saying to me, that they were astonished that it could be so clearly set in the past, so clearly evoking the past, but offering not just a way in but talking about issues that we can all think about today," she says. "Things like isolation and the need for connection, the need for touch, [gender politics], attitudes to the body, acceptance of the body, acceptance of self - all of those issues, they were saying, are remarkably relevant."

For a writer who, until now, has worked in relative obscurity, the past year has been an almostwhirlwind. Cadwallader had previously published several short stories, numerous poems, and a book of poetry in 2010, but her passion has always been in medieval literature, which became the focus of her thesis.

"I'm really interested in the literature and the ideas, rather than the history…it's where the imagination of the people is," she says. She recalls the days when she was an undergraduate student at Monash University in Melbourne, studying Middle English as a prerequisite for an honours degree in English literature. She was considered an unusual case when she proposed a thesis on medieval literature.

Perhaps it was due to her childhood memories of tripping between England and Australia. Her parents were "ten-pound Poms" who could never quite decide which country was home, making the journey back and forth three times during Cadwallader's youth. They eventually settled here, "semi-unhappily", when her two older siblings refused to budge. Cadwallader says she has "never been a huge fan" of England, but still has memories of the dark Midland skies, similar to those of the book's setting.

When her academic husband, Alan Cadwallader, accepted a position at the Australian Catholic University and the couple moved to Canberra – with all four children having flown the coop – she decided to focus on her novel full-time. They settled in Murrumbateman, a small village 30 minutes north of Canberra, and she got to work.

Five and a half years later, she is still reeling from the positive reactions even the early drafts elicited; her most recent memory of England is of a meeting in the Faber offices in London and being so overwhelmed that she could barely listen to what the publisher was saying. Meeting her husband afterwards, she could only tell him it was "nice things".

"I wish I'd taped it!" she says now, laughing. It was also in London that she sat back in awe as her Australian and English agents together struck a publishing deal. The advance, while nowhere near the sphere of, say, Hannah Kent's spoils from the phenomenally successful Burial Rites (Kent is a former student), was still gratifying, given Cadwallader is 58 and has been working non-stop on the book for five years.

On the day of our interview, she is still knee-deep in proofing notes from her American publisher, which, she says, has picked up on the smallest, strangest things. Never mind what the French translation will entail – she's not even sure there's a French word for "anchoress", much less what readers on three continents will make of the novel.

Sarah, the protagonist, is a cloth-merchant's daughter who resists the advances of a wealthy lord, in favour of prayer and service to god. With few choices available to women of that era beyond marriage, she chooses the opposite extreme, and becomes the village anchoress. It is a life of extreme deprivation, not only of sunlight, fresh air and freedom of movement, but almost all human contact and almost every kind of temptation.

It is, in fact, a life that relies on a fascinating conundrum.

"I think I really spent a lot of time thinking about how if you cut off that sense of sight, you're going to enhance the other senses," Cadwallader says.

"There's quite a bit written about the paradox of asking these women to deny their body, to shut down their senses, to contain taste and sight and sound and touch and smell, but putting them in a position where they're going to be thinking about that all day because they're being asked not to."

Not surprisingly, the novel, while pervasively gloomy, is at times almost unbearably sensual – the smell of food, the sound of music in the village beyond, the taste of an apple, the memory of a man's touch. Between her four, rough-hewn walls, Sarah's senses are constantly crackling, even as she tries desperately to dampen them down with prayer and self-chastisement.

"She's caught between wanting to do that and hearing that she should, but everything about her experience is taking her in the opposite direction," she says.

Cadwallader herself is not religious, but considers herself a spiritual person.

"I've been connected with the church, but … I have massive problems with the institution. I know some absolutely wonderful people who are in the church and I know of some terrible things about the church and the way the institution functions, so I hang loose to it. But I've always had an interest in a sort of spirituality," she says.

"For me, it's a sense of really the wonder of the world and of what we're capable of and that we're capable of knowing more. That's a vague way of putting it. It's hard to find words. It's about an inner journey, I think, inner awareness, if that makes sense."

On that level, she can identify with someone like Sarah and her quest for inner transformation. She has visited medieval churches in England, and seen what remains of these cells – often just a slit in the bricks, and the ghostly outline of a roughly built-on wall – and understands there are still women who choose such a life, with varying intensities.

But she is most interested in the concept embodied by the poet William Blake, "to see the world in a grain of sand".

"If you narrow things down, you don't narrow down your awareness, you open it up, if you take away all the clutter," she says. "So I actually am really sympathetic of that idea of what it means to be silent for two or three days, to live within silence as well. I really understand that, and I have done that kind of retreat where you just go away and it's just you. That's a very enriching thing, so I'm sympathetic to some of the thinking behind it."

In fact, it's an impulse that emerges all over the place, in various guises. Think of Jessica Watson setting out on her little pink yacht, Cheryl Strayed hiking the Pacific Crest Trail alone, Walt Whitman tucking himself away in the woods to write.

"The contemplative aspect of it is very real, but what else goes with it is what makes it so different," she says of the anchoresses. "In that sense, when you put it alongside all those other things, it's extreme but it's not as unusual as it might sound. I was really interested in that process of moving from just hibernating to developing strength."

The Anchoress is published by HarperCollins at $32.99.