Still, he's well-informed about economics: "That stuff has become common knowledge in Ireland. Tragedy has reattached itself to emigration, with people going abroad for work. There are ghost estates where companies sold houses then folded. When we had storms recently, fences started flying around, because they'd just been placed between crooked concrete posts and left."
Born in Tipperary in 1976, Ryan grew up reading American writers - Saul Bellow, Ernest Hemingway, John Steinbeck - then, in his 20s, discovered the Irish authors John McGahern, Patrick McCabe and Roddy Doyle. When I mention the late Dennis O'Driscoll who, like Ryan, combined writing with a civil service career, he says, "Every poem of his nearly makes me cry."
Did he always want to write? "There's a box of unfinished crap in my parents' attic that I can't get because I'm scared of the spiders up there. When my wife was pregnant in 2008, I decided, 'I can't be this guy who claims to be a writer but never finishes anything.' It was the prosaic notion of not wanting to set my child a bad example, wanting to be able to tell them in years to come: 'I wrote a novel.' Even then my wife had to drag me through it. I kept saying, 'I'm not a writer, I can't do it'."
Johnsey is hard on himself too but his biggest problem is that he stands out. "I was surprised to see somebody describe him as 'mentally deficient'," says Ryan. "He's just a really unworldly aggregation of every bullied person I've known. Things happen to Johnsey that I witnessed, especially in school. People got such a hard time there, your heart breaks to think about it."
The reader's affection for Johnsey grows as we follow him, but Ryan's commitment to exploring the ways that circumstances shape individuals means that, even when Johnsey is savagely beaten by four young "yahoos", they're clearly the product of a deprived, macho culture. "I have fond memories of the village where I grew up but there was all this madness and oppression. Lots of men play along with an idea of what a man should be, which makes them unhappy. Violence is an extreme form of that."
Johnsey's recuperation in hospital is the novel's turning point. The first half of The Thing About December portrays his unhappy youth but the second contains
laugh-out-loud moments, even as his neighbours try to force him to sell the farm to developers.
"I try to have levity there all the time, although Dave's comedy is more overt," says Ryan. Mumbly Dave is Johnsey's fellow patient, his brash brother in temporary blindness, and the pair tease their young nurse, Siobhan, aka The Lovely Voice. Both characters befriend Johnsey, and he must decide whether to trust them, but the depiction of sharp, gutsy Siobhan is refreshing. "I write women the way I know them," says Ryan. "We're seeing women on exactly the same plain as men for the first time and nearly all the women characters in my books have inner strength. That's probably to do with my mother who's funny and forthright."
Ryan admires his contemporary and compatriot Eimear McBride, whose prize-winning debut, A Girl Is A Half-Formed Thing, was another surprise success last year, although he resists my attempt to place the two at the forefront of a renaissance in Celtic stream-of-consciousness fiction. "Eimear is in the avant-garde and I wouldn't see myself in that." Their work offers separate visions of religion because, whereas Catholicism compounds misery in McBride's novel, Ryan's characters conjure acerbic responses to its teachings. "I know the church inflicted suffering, and I've seen people use religion as a stick to beat others," he says, "but my experience of the Church of Ireland is largely positive. In the gospels, you find tales of people's struggle to be heard. I honestly think all Jesus was saying was: 'Love your neighbour'. Going to Mass with my parents was a nice thing and not really to be taken too seriously."
Does he take literary success seriously? "My work and family routine are the same as ever but it's the most amazing thing and my writing career has changed no end. I can't believe it's happened. I keep expecting to wake up." He was excited to receive a congratulatory email from fellow Booker nominee Colm Tibn, so the rave reviews, which The Thing About December has been garnering from senior Irish novelists, will mean a lot.
After a phenomenal 18 months, when The Spinning Heart won Book of the Year at the Irish Book Awards and the Guardian First Book Award, what is he hoping to achieve this year? "I probably need to take time off from the civil service to finish my third novel. I'd like to be a full-time writer. I'd love to drop the kids at school, knowing I had eight hours of writing ahead of me."
There are plans to adapt The Spinning Heart for the stage, Ryan has written eight stories, which might form a collection, and he's working on a novel about a pregnant woman. All three projects are in their infancy, however, so let's end with something he says when conversation circles back to the recession which, I think, encapsulates the spirit of his work: "The crash stripped away the film that was over our eyes. We started to see each other as we really are."