“The constant genius of Irish letters,” according to Sebastian Barry, a “first-rate novelist” for Richard Ford, and “one of the most original and disturbing writers since Jean Rhys”, wrote Linda Grant. They were all referring to the Irish novelist Deirdre Madden. When I first meet Madden, I am immediately reminded of one of the characters in her latest novel, Time Present and Time Past: Colette is “inordinately kind, and this kindness, suffusing her face, makes her look more attractive than many a cold beauty half her age”. She is a character who embodies one of the central qualities of Madden’s work: a profound and wide-ranging compassion.

It’s there in her first novel, Hidden Symptoms, which came out in 1986, and in her second, The Birds of the Innocent Wood, which won the Somerset Maugham award in 1989, and in her third novel, Remembering Light and Stone. And it’s there in all the novels that follow: in her fourth Nothing is Black, for example, the central character talks about a painting she has bought from a friend, “a touchstone from which she would draw strength, and realize the need for compassion”; in Molly Fox’s Birthday, which was shortlisted for the Orange prize in 2009 (the second time Madden was shortlisted for the prize) the narrator realises that compassion was “one important part of the mystery” of her friend Molly Fox’s brilliance as an actor. She “never judged a character”, says the narrator, whose name we never learn. Nor, it’s clear to anyone reading her work, does her creator.

In Madden’s early work, the compassion went along with a deep sense of melancholy. The prose might be a joy to read but there really wasn’t all that much joy in her characters’ lives. In Hidden Symptoms, Theresa is recovering from the brutal murder of her twin brother; in The Birds of the Innocent Wood, Jane grows up in the shadow of her parents’ sudden death in a fire. “The year has barely begun, but she knows that it is foolish to expect that it will bring any hope,” is a thought that gives a flavour of fiction that’s rich in poetic meditation, but which it would, to paraphrase PG Wodehouse on the Scots, be hard to confuse with a ray of sunshine.

It’s the kind of fiction that might make you think its author had a traumatic childhood, but Madden apparently didn’t. “I’m very close to my family,” she says. “We’re all very fond of each other.” Born in 1960 into a Northern Irish Catholic family, she grew up in Toomebridge, a small village “right beside the north shore of Lough Neagh” in County Antrim. Her father was a sand merchant and her mother was a teacher who gave up work as soon as she got married. She had one sister and a “very quiet” childhood, spent reading: Enid Blyton, E Nesbit, comics, anything, she says, “I could get my hands on”. In her teens, she discovered Edna O’Brien and Elizabeth Bowen, whom Richard Ford has said he thinks of when he reads Madden.

“The Troubles broke out when I was a child,” she says when I ask where the melancholy comes from, “so that really coloured it very much. I think it had a very big impact on pretty much everyone I know who lived through it. “ So is that it? Or is there also something bigger to do with Irish rural life? I’m thinking, I tell her, of John McGahern, whose sad, luminous work is about as beautiful as melancholy gets.

“It was a very depressing time,” she says, “but I think Northern Ireland, even in terms of climate, is a tough place anyway. One thing that does strike me if I think about my own work is how the Troubles are almost always in it in some way, at some level.” They are most visible in Hidden Symptoms, but there’s a sense of them in the background of nearly all her books, even though most aren’t set in the north. But there is, says Madden, another, much simpler reason for the melancholy. “Often,” she says with a smile, “one tends to be quite gloomy when you’re young.

“There was “great encouragement to work very hard, and to get to university”, which she did. She read English at Trinity College Dublin, and instantly felt at home. She had started writing “little bits and pieces” when she was in her teens and soon realised that she wanted to devote her life to writing. Her first short stories were published in The Irish Press by David Marcus, who, she says, gave “many Irish writers their first break”. The stories were published while she was still at Trinity and spurred her on to do the MA in creative writing at the University of East Anglia, which set so many other writers on the path to literary success.

She wrote Hidden Symptoms, finished The Birds of the Innocent Woods and was picked up by Faber. Back in Dublin, she met the poet Harry Clifton and married him. She is still dedicating her novels to “Harry, with love”. “We thought we’d travel a bit and see how it goes,” she says, “and we ended up staying out of the country for about 16 years. “ First, they went to Italy where they lived for two years. Spells in London, Switzerland and Germany followed and then Paris, where they stayed for 10 years.

It all sounds pretty idyllic. “Well, it sounds like it,” she admits, “but it was quite stressful in its own way. There wasn’t much money. We’d use one writer’s bursary for two. But we were both getting published, and the books were coming out. That was the main thing.” Light and Stone, her novel about a young woman living in Umbria, is full of poetically precise descriptions of architecture and art. Nothing is Black continues the theme. Claire, the painter at the heart of it, “refused to believe that by writing about apples you could ever say much about things that weren’t about apples, but when you thought about a Cézanne painting of a bowl of fruit, it expressed knowledge of other things - mortality, kindness, beauty - in a way that was only possible without words”. Does Madden wish she could paint, too? “It would be great,” she says, “but I think to do it, it would have required a decision of the dedication I’ve given to the writing, and I don’t think I could have done both.

“Now that she is teaching writing at Trinity she has to squeeze her own work around her job. But she is still very disciplined. “I always think that writing is much more of an artisan activity than an intellectual activity. It’s a very messy, ungainly, unwieldy process. It’s more like weaving a very big rug.” Each novel, she says, is “a bit like dreaming in reverse”. If, she explains, “you have a very, very vivid dream and you try and describe it, it all gets very hazy, whereas with writing it starts quite foggy”.

Time Present and Time Past took four years “on and off” to write. It’s set in 2006, just before the economic crisis, but she didn’t want it to be a “Celtic Tiger novel”. Time, as you might guess from the title (taken from Eliot’s The Four Quartets) is a big theme: the way it can appear to contract and expand, how we remember the past, and the readiness to forget that we’re all alive at a particular moment in history. But it’s also a novel about family life and, unusually for Madden, a largely happy family life. It’s quite different in feel to her other novels. It’s lighter, and at times funny. It is, in fact, more like the charming children’s books she has started writing.

These - Snakes’ Elbows (2005), Thanks for Telling Me, Emily (2007), Jasper and the Green Marvel (2011) - came about when she found herself “in bookshops going down the back and reading little books very quickly and enjoying them immensely”. She gets, she says, “the best fan mail ever”. She doesn’t have children of her own, and it’s clear that these letters, “written in wobbly pencil”, are a big source of pleasure. Her friends, she says - and I have to admit I’m surprised to hear it - tell her they have much more of a sense of her personality in her work for children than her work for adults. “It’s a great thing to make kids laugh,” she says.

And it’s a great thing to write sad, beautiful books and still be able to say that “one gets more cheerful as one gets older”. “The next book is always the one that’s going to be better. Even if you’re happy with the work, you always feel you can do more.” Her next novel, she says, will be lighthearted. Have I, she asks, ever read Thomas Mann’s Confessions of Felix Krull, Confidence Man? I shake my head, and she nods kindly. “Most of Mann’s work,” she says, “is very serious, and then late in life he produced this very funny book. I would like to write something like that.”