'You could write about this fat bastard in Central Park," Colum McCann laughs down the phone, enthused by the idea (his) of talking about his new book TransAtlantic even as he heavy-breathed his way through an habitual five-mile run through Manhattan's pastoral retreat.

Scan the decades of other National Book Award winners and it is difficult to imagine William Faulkner, say, or John Cheever encouraging an image of them at their least tweedy and bookish and with bare-naked shins on show. But McCann has made his slow-burning ascent to take his place as one of the most recognisable names in international literature without ever losing his reputation for affability and a heartening lack of preciousness.

Anyway, the idea of talking about his book on the move is apt because his new novel is all about the to-ing and fro-ing of the Atlantic expanse which has defined the relationship between Ireland and America for centuries.

Real and imagined people make the voyage through maritime travel and aviation in TransAtlantic : John Alcock and Arthur Brown on their historic flight from Newfoundland, which ended with a makeshift landing in the heather lands outside Clifden; Frederick Douglass to famine-scourged Ireland and Senator George Mitchell on the most important of his interminable journeys to Belfast during the climactic weekend of the peace talks in Easter 1998. And, in fact, the day after McCann bounces into the Saborsky cafe, fresh and high-humoured after his run, he will take the same flight himself as he embarks on the turbulent period which follows the publication of his books.

McCann has lived in New York since the mid-1980s and, like most long-term immigrants, he knows the corridors of JFK and Dublin airport like the back of his hand. But he is still prone to the psychic trauma of hurtling across all that ocean and of swapping the new world for the old and familiar.

TransAtlantic resurrects Famine-era Dublin and Cork but is in essence an ode to Belfast and its future. On Friday, his book was launched at the Ulster Museum in Belfast and as he considers his follow-up work to Let The Great World Spin , he admits that TransAtlantic has taken him more closely to the heart of his home country than any book since his debut collection of stories.

"Yeah, I will be honest: this is my Irish book," he says. "I have been preparing for a long time to go home - in Dancer , I didn't even mention Ireland. The whole structure for this book was originally going to be about an African professor living in Ireland and examining Frederick Douglass. That was my original perception but it didn't work out that way."

Instead, he has produced an interwoven narrative which spans centuries and generations of people who move through their narrow worlds unaware of the consequences their lives will have on future generations.

The story contains dauntless women and ferocious hardships and a tersely gripping account of Alcock and Brown's bleakly wonderful journey in their Vickers Vimy. Imagined characters mingle freely with the two figures of international political importance, both of whom became hugely important to McCann in the process of writing the book.

Famine and Empire
McCann admits to having felt ambivalent about Douglass as he studied the period of his four-month visit to Ireland, a trip distinguished by his enlightened reception and by Douglass's reluctance to ruffle the feathers of the British Empire in any of his speeches even though he was witness to the appalling consequences of the Famine.

"So I was wondering: it is almost like the Celtic Tiger narrative – aren't we so acutely engaged with the world and sexy and cool that we invited this man into our arms. But there was this other narrative, which is much more cynical, which is that he was an Anglophile and a dandy and anti-Catholic. I didn't like either narrative and increasingly it became clear to me that it was more interesting to dwell in both. So I liked and disliked him. I wanted to cover both aspects and for the politics to confound him as much as me.

“And ultimately Douglass said: for everything that is happening in Ireland, there is nothing I can do. These people are not enslaved. And I must speak out about slavery. I must cleave to that one thing. And then I began to think about my own, very small, anonymous corner.

"So here I am, living beside Central Park and I can come here to the cafe Sabarsky. Literally five miles up the road is the worst county in the United States – in the south Bronx. It is poorer than Alabama. Am I up there writing about those people? No, I am not. So will people say I am not morally responsible in that case? So you have to juggle these things.

“And suddenly you have a more shaded view of Douglass. I think he would recognise certain things as being true in this book. The only gauge I have for that is that I also did the Mitchell section without meeting Mitchell and I feel certain that is accurate.”

Enthusiastic torrents
McCann talks in great, enthusiastic torrents, one idea flowing into the next. Agonising over the moral choices within his writing his nothing new for him: when he was writing This Side of Brightness in 1998, he spent considerable time in New York's warren of tunnels with the habitués of that underworld and even though he wrote the book fearlessly, he continually questioned his right as an outsider to breeze into their lives and make fiction of it.

In TransAtlantic , he took a similar risk when he felt compelled to concoct his own version of Mitchell, just as he had Douglass. On some abstract level, he felt there was a connection between them –"Without Douglass, there would be no Mitchell." It was one thing bringing to life a man who died in 1895 but quite another to insert into his fiction an interpretation of a man who lived just a 15-minute walk from McCann in Manhattan. So he wrote to the Mitchells and began a correspondence with the senator's wife, Heather. "I asked for their blessing and told them that they would have full access to the manuscript." He spoke with diplomats and European politicians who knew Mitchell. He wrangled half an hour on the telephone with Tony Blair.

The more he heard, the more fascinated he became by Mitchell: a quintessential son of Maine – laconic and understated and, as it transpired, possessed of a genius for moderating and tempering the flushed intransigence of political debate in Northern Ireland.

“Of all the people I have come across in the political world, there is nobody like him,” McCann says sincerely. “He is a good man. We don’t have a whole lot of them! And then the fact there are murals of Douglass in Belfast, even if they are misinformed. Mitchell is a great story – a 64-year-old man who has just had a baby and he is asked to go over and broker a peace process in a place that has been fighting for 700 years. For nothing! No pay! And how did his wife deal with it? He is gone five days a week.

“I didn’t meet him until after I had written that section. And I knew how he would respond – this is just too nice a portrayal of me. But I believe that that is who he is. And this is the most important moment in Irish history for one hundred years. I remember going up to fucking Garvagh [his mum’s home place] and changing bus in Armagh and the British soldier coming on board. Walking up and down the aisle, me trembling with my anorak turned inside out because of its Free Ireland patch.”

He roars at the notion: every second teenager in Ireland was sporting quasi-rebellious badges in the 1970s and it is easy to envisage McCann among them. He has always been a curious blend of undiluted Irish and international beatnik, disregarding the advice of his father Sean, who was a beloved features editor at the Irish Press group, not to become a journalist by doing just that. He remains fascinated by his formative years in the trade, warmly reminiscing about his period at the Connaught Telegraph and of the thrill of interviewing Con Houlihan and of seeing his byline.

But he kept moving, famously embarking on a picaresque bicycle tour of the United States and finding his voice as a fiction writer. New York has been his home for 25 years and it is to his credit that he can sit easily at the round table of the literary scene in the metropolis without acquiring any of its pomposity. America’s openness to outside literary voices is a constant source of delight and amazement to him.

"The way Aleksander Hemon can write about Bosnia and Chicago and be both Bosnian and American and that is fine here – it is fucking unbelievable, the generosity involved in that," he says. Similarly, he – a true-blue Dub – was permitted to invent the phantasmagoria of 1970s New York, with Philippe Petit's fabulous tightrope work of the brand new World Trade Center towers as his central allegory, and there was no backlash when Let the Great World Spin was published in 2009. There was no questioning the validity of his voice or pointing out that he was not from there. Instead, his novel won the National Book Award and was thereby placed alongside Sabbath's Theater and The Moviegoer as a seminal American work.

That freedom of expression feeds into his thoughts about Ireland. Gabriel Byrne, a friend and another hero to McCann, comes up in conversation. With some justification, he feels the actor's deep and unselfish commitment to Ireland was badly misrepresented through the interpretation of his comments about the Gathering.

'Gabriel is a patriot'
"That is where Gabriel comes in. It is about being able to criticise ourselves and be generous with ourselves at the same time. The fact that he got reduced to a soundbite was so sad. He is a patriot. We will be talking about patriots in three years. Gabriel has been reinventing history for a while. He is challenging people about how they look at Ireland. He cares about the country. He worked for three years as cultural ambassador. He was completely unpaid à la Mitchell. He thinks hard about the country and wants to see the best for it."

McCann clearly cares about Ireland and nods his head at the mention that many people would probably wonder why therefore, he doesn’t go and live there.

“It is a great question. And the answer is . . . I don’t want to live there. I have family here, Alison, my wife, is from here, we have three kids. And because I am happy here. But I can engage with Ireland intellectually and poetically. Would I have written about the peace process if I had been in Ireland? Joyce said in a letter: ‘I have lived so long abroad and in so many countries that I can feel all at once the voice of Ireland in anything.’ That is certainly what Gabriel has been talking about and I feel that is what I have been talking about too.

"The book is dedicated to Loretta Brennan Glucksman. She is . . . a queen. The queen – we laugh about it in this group that gets together to try and raise funds or have a cultural festivals and what not. And she is the glue in everything. So I consider her to be a patriot and she is American. And listen, I can understand someone reading this and going to the pub and saying: your man McCann is a fucking asshole . . . there he is spouting his mouth off about Ireland and living in New York. It's all very well for him. I understand that.

"It's like that Walt Whitman quote. 'Do I contradict myself? Very well then, I contradict myself.' But I think my voice is more important outside of Ireland than inside. Is that to say I won't go home? I might well spend the next 20 years there. I don't see it on the horizon right now. So maybe I am shooting my mouth off but that is how I find it. There are ways to engage with Ireland. I can't give you a clean answer... except that I want to be here."

Then he goes home to pack for his flight.

TransAtlantic is published by Bloomsbury. Colum McCann is appearing at Dublin Writers' Festival tomorrow , and at Listowel Writers' Week on May 30th