Graham Norton’s second novel, A Keeper, had not gone to press before this interview, so his publisher ran off an A5 photocopy for me. After reading the first few pages, I thought they must have sent me the wrong book. Literary fiction this strong could not be the work of a TV star whose canon of previous works comprised one novel. Whoever wrote this clearly had to be an established author.

When I tell Norton this, he does a little squirm beside me on the sofa. “Oh my God, that’s incredibly nice of you. I’m not very good at taking compliments, so let’s gloss over this bit, but I’ll just say thank you very much. Seriously, that’s really, really nice.”

My very next thought, I confess, had been: “Or else he used a brilliant ghost writer.” But when I asked his publicist, she had become quite indignant and confirmed it was entirely Norton’s work. She admitted, however, that almost everyone else had jumped to the same conclusion, so I wonder if Norton found that flattering or insulting.

“Well, it’s flattering, I think, because my big worry when I began trying to write fiction was that being Graham Norton off the telly would overwhelm the book and that people would feel that I was reading over their shoulder,” he says.

His 2016 debut, Holding, was widely praised by critics impressed by his success in absenting his TV persona from his prose. Second time around, though, he fears readers may be less generous.

We’ve got to thank the church for what Ireland is now, because it is a reaction to all those decades of darkness

“I think there will be some backlash on this book, just because I think people’s expectations of the first book were so low that actually a lot of the favourable press were like: ‘This isn’t nearly as bad as I thought it was going to be,’ which is almost like saying it’s good,” he says. “So I think there will be some people who then went ahead and read that book and thought: ‘Actually, it’s not very good.’ So now they’ll have a go at this one.”

How much would he mind? “Well, I’ll prefer it if people liked it, but I’m pragmatic about stuff like that. I understand how it happens. And also, you know, they may well be right.”

Whether the last sentence is false modesty or genuine self-doubt is hard to tell, but either way it is quite unnecessary – I would bet my house on A Keeper being a hit. The novel is a darkly comic tale of family secrets, spun from shame and woven through generations of men and women from rural Ireland to Manhattan.

At the heart of the book is the fate that befalls an unworldly spinster, Patricia, who places a lonely hearts advert in her local newspaper. The farmer who writes back to her sounds unexpectedly – and thrillingly – promising, but turns out to be a tongue-tied dullard. The disappointing discrepancy between the man and his letters baffles Patricia, until she discovers they had in fact been penned by the illiterate farmer’s terrifying mother, whose sinister motives become slowly and appallingly clear. The legacy of her monstrous scheme plays out through younger generations, in a cycle of secrecy and loss that evoke familiar Irish themes of repression, shame and above all motherhood.

The phenomenon of a family repeatedly recycling its troubles through generations is widely recognised, but not easy to depict. Norton manages to make his story’s uncanny repetition of apparently random misfortunes feel perfectly plausible – but how does he explain why it happens? “Well, I really don’t know. We all know those families who are visited by tragedy after tragedy after tragedy, but you sort of think how can that be, you know, is it their fault? It’s extraordinary.”

Having not believed in God since his teens, he cannot put it down to divine destiny. He does, however, think the church has something to do it. If unresolved family secrets are the root of generational cycles of ill fortune, Roman Catholicism’s culture of secrecy has made Irish families particularly vulnerable. The only good thing Norton can say for the church is that public disgust for its abuses has helped inspire the popular surge of progressive opinion in Ireland today. “We’ve got to thank the church for what Ireland is now, because it is a reaction to all those decades of darkness. If the church had been more moderate, we’d still be in gloom. But because they kept people in darkness for so long, we’re now sitting in light.”

Facebook Twitter Pinterest ‘Does he worry about turning into a diva? “Oh God, yes, all the time!”’ ... Norton with (left to right) Bradley Cooper, Lady Gaga, Ryan Gosling, Jodie Whittaker and Rod Stewart on his chatshow. Photograph: Matt Crossick/PA

Recent referendums legalising gay marriage and abortion, he grins, “are a big fuck-you to the priests who are telling people to vote against those things. People think: ‘If every other fucking thing you told us is fucking shit, I think I will do the exact opposite of what you’re telling me to do.’ Which means that, oddly, in a world that seems to be going to hell in a handcart, Ireland is this wonderful beacon.”

Norton was only 20 when he left Ireland, first for the US and then the UK, but he thinks, if he were 20 and gay in Ireland today, “I might very well stay. You wouldn’t want to get on a boat and come to here [the UK], or you wouldn’t want to get a boat and go to America, and those were my two big options.”

I find it a struggle to picture Norton anywhere other than our TV screens. For 20 years, we have watched him scandalise celebrity guests with risque innuendo and dare audience members to reveal their most personal, usually embarrassing, anecdotes. The achingly hip private members’ club near his east London home where we meet looks like his natural habitat – but he says he will spend the whole summer in west Cork, where he feels truly at home. “That is the world I come from, which is why I’m writing about it – because I feel like I know it.”

I find it hard to reconcile the Norton who writes – with the finely observed affection of a native – about inhibited and under-realised Irish lives with the London TV star famous for garrulous indiscretion. But then I have an epiphany. Perhaps, I suggest to Norton, his TV career has been a rebellion against his childhood culture, that getting people to talk has been his mission to undo repression.

I am rather pleased with this theory – until Norton says I have got it all wrong. It is true, he agrees, that traditional Irish culture is not big on confessional intimacy or emotional disclosure. “We don’t do that in Ireland. But we will tell you a story. We will tell yarns. And that is exactly what I’m doing on TV. I just try to get people to tell stories.”

People get stuck in their heads about the thing that’s wrong with their life – they forget to have a lovely time

He has been doing it since his first chatshow on Channel 4 in 1998, but before that he had been a jobbing actor and bartender, so I wonder where he learned how to interview people. Is it a skill he trained himself to master and could teach anyone – or is it an elusively mysterious gift, more like a magic trick?

He considers the question carefully. “I think it’s innate. But, then, a psychology student did a thing quite a long time ago on YouTube, all about how I sort of make people like me. He goes through all these clips, analysing my techniques. Apparently, I do a lot of arm-touching and he said there were all these rules I was following. Like: ‘He opens with a compliment, but then he’s self-deprecating and then he undermines the compliment.’” Norton looks appalled. “And it’s like: I do do all that! But it’s not conscious. So, I had to stop watching it after a few minutes. Because if you became self-conscious about it, that would be terrible.”

Presenters who slog away at perfecting their technique must be wild with envy about Norton’s effortlessness, which must be made all the more galling by his successful detours into TV drama, musical theatre and radio. There is one thing he is rubbish at, though, that he wishes he could do well. “I wish I could catch or throw a ball,” he offers without hesitation. I think he is joking, but he is not.

“It’s a male thing. It’s a boy thing. Yes, and it has [affected me] all my life and at 55 to still be humiliated …” He shudders. “I think it’s why my dogs aren’t very interested in playing ball, because they look at me and they’re thinking: ‘Fuck knows where that’s going to end up, you know, he’s aiming over there, it could end up behind his shoulder, it could end up at his feet.’” Does he not have use of those bendy things that look like a shoe horn and hurl the ball across the park? “No, because I doubt I could do that, either. Yes, it’s quite serious. I was in my late 4os when I learnt how to flick stones, you know, make stones bounce, and it was one of the proudest days of my life. It’s pathetic, isn’t it?”

Apart from that, Norton cannot think of anything he feels insecure about. He is glad he did not become famous until he was 35, old enough to dodge most of the classic mistakes of younger stars. He strikes me as unusually grounded, but when I ask if he worries about turning into a diva, he exclaims: “Oh God, yes, all the time! You’ll say something at a dinner or something and you’ll get the distinct impression that what I just said has not resonated with the room. Yes, you’re just being a tosspot. It’s like when guests come on the show and try and tell an anecdote about how their flatbed on the plane wasn’t really flat; the audience scratches its head. So, yes, you do check yourself about all sorts of things.”

If Norton’s success has come at a price, it has been his difficulty finding a man content to be eclipsed by his celebrity. Having “failed all my relationship exams”, as he once put it, he has now been single for several years. He always claims to be happiest that way, but when I ask if he hopes to fall in love again, he concedes: “Well, to share bits of my life, yes. I think that’s probably been one of my problems in the past, the full-on commitment. I think I’ve looked to relationships for everything – and they provide some things, but not everything.”

I think Norton must understand the loneliness of singlehood, because parts of A Keeper ache with longing, so I ask what he misses about being in a relationship. He doesn’t exactly answer the question – but he does make me laugh.

“It’s something I say to people all the time. Enjoy the life you are living, don’t mourn the one you’re not. I think so many people get stuck in their heads about the thing that’s wrong with their life, like being single, that they forget to actually have a lovely time. It all boils down to something pretty simple. If you want someone to share your life, look fucking happy!” He lets out a mischievous cackle. “You know what I mean. If you’re miserable, no one wants to share that. Yes, that’s my advice.”

A Keeper by Graham Norton is out now (Hodder & Stoughton, £20). To order a copy for £17.20, go to guardianbookshop.com or call 0330 333 6846. Free UK P&P over £10, online orders only. Phone orders min P&P of £1.99.