When the old folks in the family start banging on about their parents or their childhood or - heaven help us - “the war”, most of us tune out or slip away. Not Sebastian Barry. He listens. He remembers. Then he takes the half-buried memories and dusty details, the detritus of long-ago lives, and turns them into literary gold.

On one level, Barry’s family detritus is no more exciting than anyone else’s. Among the less promising components of the research for his new novel The Temporary Gentleman were some random bits and bobs he came across in a drawer: a box of military medals, a set of false teeth, an old accounts book. At the beating heart of his novel, however, is Barry’s intense childhood connection to his maternal grandfather, Jack O’Hara.

“The very first thing I wrote when I was maybe 21 was six stories about him and me going around the place - not realising, because I was too young to realise it, that as a grandfather, that was the most magical and important thing you could do,” he says. “Bring the kid with you when you’re going west. Because if he hadn’t brought me with him when he was going west - numerous times - to see his parents, my great-great grandfather, I wouldn’t have anything to write about.”

A room in Monkstown
Ask Barry a question about The Temporary Gentleman’s central character, Jack McNulty, and he’ll answer with a story about Jack O’Hara. “We shared a room in Monkstown [Co Dublin] for most of my childhood,” he recalls. “I knew things about him that you probably shouldn’t know about anybody - his private habits - and I helped him through various ailments and so on.

“He loved telling stories. He had been everywhere in the world. The northwest frontier, the landscape of the Hindu Kush, was one of the great landscapes of my childhood because he used to evoke it with his stories. He taught me the sequence of ranks in the British army when I was about eight. I was in the bed with him while he told me everything about his life, except probably, the real things, because of course you couldn’t go there.”

Many of the stories about his grandfather, which Barry has recreated in the book, he first heard in the form of a diatribe from his mother, the actress Joan O’Hara, a woman who knew how to deliver a dramatic monologue. “While he was alive, it was always weighted against him. All her stories were for her mother and against her father.”

It rapidly becomes clear to the reader of The Temporary Gentleman that Jack McNulty is no angel. Many of Barry’s characters are caught up in the storms of history: Willie Dunne in the trenches of the first World War in A Long Long Way; Eneas McNulty in the cross-currents of the Irish War of Independence in The Whereabouts of Eneas McNulty. Here, though, Jack, an engineer who has worked in bomb disposal for the British army, struggles against a perfect storm of his own making, in the shape of over-indulgence in gambling and alcohol.

It’s nothing new for Barry to be digging around in difficult parts of his family history. The story of a great-aunt who was confined to a mental hospital provided him with the character of Roseanne in The Secret Scripture; the physical disability of another great-aunt was the inspiration for Annie Dunne; a third great-aunt became Lilly Bere in On Canaan’s Side.

A rift in the family
This fictional appropriation of family lore led to a serious rift between Barry and his grandfather in the 1980s. Now, a quarter of a century after Jack O’Hara’s death - “something he sincerely did not wish to do; he was totally against dying,” Barry says with a smile - the author is convinced it is the right time to tell this particular story.

“I’m a little older now than my grandfather was when I was born,” he explains. “I’ve had my three children, and I’m having my marriage, and I see the difficulties. And I see that the challenge given to us in being alive is immense. I’m trying to understand the cards he was given and what sort of game he played for himself.”

As a novelist, his job in this instance has been to act as a kind of ghost writer. “He set out to write his memoirs in that old accounts book, which I still have somewhere,” says Barry. “But he only ever filled the first three pages, which was the dutiful itemising of his possibly dubious ancestry. As soon as he even got to childhood he was in trouble, because of his mother not knowing her own family background. He screeches to a halt after three pages. So in a way, this whole book is like a 30- or 40-year delayed release. And I cannot tell you the strange joy of doing that - the feeling of being at his elbow as he finally fills this blasted notebook.”

The novel’s spectacular opening sequence, in which the ship on which Jack is travelling to Ghana is hit by a German torpedo, was inspired by a chance remark from another of Barry’s relatives.

“Pat O’Toole was from the Aran Islands and was married to my aunt Mary. He knew my grandfather pretty well, warts and all, and he told me something that my grandfather had never told me. I don’t know if it was a bar-room remark or what, but he said to him, ‘You know, Pat, three times in my life at the war, drink saved me. Alcohol saved me. Once when I was torpedoed, once when I was nearly blown up, and another time when I was in a car accident in the Hindu Kush. If I hadn’t been functioning, but blind drunk, at the time I’d never have survived’.

“Pat just said that to me a few years ago. And I remember it, that little moment when your brain goes ‘click’ and puts it somewhere, and you know that you’ve been given something really crucial. New ground. A new field to plough.”

A matter of stepping back
With two Booker nominations, a Costa Book of the Year award and a James Tait Black Memorial Prize under his belt, Barry is consistently named as one of Ireland’s top literary novelists and finest prose stylists. But for Barry himself, style is a matter not so much of control as of stepping back.

“I think a writer needs to have the gift of absence,” he says. “It’s a matter of trying to get as close as you can to the actual syntax of the person. I believe that character, somehow or other, lives in syntax.

“That’s three books I’ve done now where the character has been writing their own book. In The Secret Scripture Roseanne is hiding her manuscript. In On Canaan’s Side, Lilly couldn’t care less if anyone reads it or not. Maybe it’s an attempt to get closer to them, without the authorial flourish. So that they can be alone in their own book.”

Listening to Barry talk about his fictional characters and his real-world family is slightly unnerving. It’s as if, in keeping them all in his head over the course of six novels and 16 years, he has almost elided the distinction between fiction and reality. Has he? “It’s 96 per cent made up,” he says. “But as human beings, we’re 100 per cent made up. Fiction has us beat by some margin.”