James Patrick Donleavy stands in the kitchen of the estate house called Levington Park, dressed in layers: white undershirt, checked cinnamon button-down, padded navy vest, and tweed sports jacket. Black slacks fall over tattered loafers. I believe I can see his big toe. At eighty-nine, the author of “The Ginger Man” is handsome, spry, and a sartorial medley, something of a cross between a country gentleman and a gentleman farmer. I have been ushered in by Deborah Goss, Donleavy’s secretary, who tells me on this chilly May afternoon that this room is the warmest in the two-hundred-and-sixty-year-old house. Ireland’s National Inventory of Architectural Heritage notes that Levington Park “was reputedly (re)built for Sir Richard Levinge (1728-86), a noted and colourful eccentric, to celebrate his marriage in 1748.” The current resident has lived here for forty years.

“The Ginger Man,” Donleavy’s début, was published in 1955, in France, by Olympia Press, the same press that published “Lolita,” also in 1955. The book centers on an American expat, Sebastian Dangerfield, who is studying law at Dublin University and is determined to idle away his time until his wealthy father dies on the other side of the ocean. Dangerfield has a young wife and child and no compunction; there is quite a lot of sex and lascivious talk, and few sins go unattempted. The novel was banned in the U.S. and Ireland, but despite—or perhaps, in part, thanks to—its rocky start, the novel made its author two things: a celebrity, and a lot of money. The latter, presumably, has allowed Donleavy to inhabit this still grand, deflated realm: the rusted gate, the mold at the top corners of the walls, the drippy ceiling, what Irish writer Anthony Cronin called “that smell of money gone which was once so prevalent in Ireland.” “Some place. What holds it up?” I think. This is a line from “The Ginger Man.” (The answer, in the book: “Faith.”)

Donleavy asks how I arrived. By rental car, I say, though that’s not what he meant. “By ship or plane?” he clarifies, and I can’t tell if he is joking. In Donleavyland, it is yet conceivable for a man to travel by steamer. “You know, you’re so out of date that it doesn’t matter”—another line from one of his novels. The remark, in the book, is complimentary.

“Nothing has changed in these places here,” Donleavy says. He bought the house and the two hundred and fifty surrounding acres—it’s a working farm—because of the relative solitude. “Here you had space where you could just go out and everything is quiet. This became a rather pleasant sort of place to spend your daily life.” He is drinking tea and grapefruit juice, nibbling at an array of pastries, and nursing an infected eye. Born in Brooklyn and raised in the Bronx to Irish immigrant parents, he is what the Irish author and playwright Brendan Behan called a “narrowback”—that is, a child of broad-backed toiling émigré Irish, whose American-born progeny had an easier life and a more svelte physique. Donleavy came to study at Trinity College, in Dublin, on the G.I. Bill after the Second World War, and here he remains, just a few miles from the town center of Mullingar, in County Westmeath.

Donleavy speaks with that curious accent known as Transatlantic English—like Katharine Hepburn, except with a beard and fifty years of living in Ireland. He says “One does,” instead of “I do,” for instance. Gore Vidal called his writing pornographic; Dorothy Parker claimed nobody could write a better novel than “The Ginger Man”—which she called “a rigadoon of rascality, a bawled-out comic song of sex”—unless that person was Donleavy himself. Sixty years later, the work remains a hilarious and upsetting portrait of postwar Ireland and the American G.I.s who showed up there, with the prerogative and the wherewithal to carouse and copulate on a level that the locals did not appreciate. Lilliput Press in Ireland is publishing a special sixtieth anniversary edition, in July, which comes with an introduction by Johnny Depp, who is also planning to make a movie out of it. Depp, in the intro, describes the novel as “a bedeviled, timeless jewel of scandalous misdeeds.”

I asked Donleavy about his childhood in Woodlawn—pleasant, he says—and then we hit upon boxing. It’s a sport he took up as a boy at the Fordham Preparatory School, and the New York Athletic Club. “There was nothing like it anywhere in America, as a structure,” he says of the N.Y.A.C. “It had wonderful kitchens, and you could stay there overnight if you liked, and you could have your breakfast delivered to your room where you were staying. And it was so convenient, right in the middle of New York.”

Many of Donleavy’s most memorable heroes are pugilists as well. “A Fairy Tale of New York” and “A Singular Man,” two later works that rival the début novel in wit and ribaldry, are set in New York City; in both, the heroes retreat to the New York Athletic Club to box, wrestle, and exhale. J.P. asks me to turn around so I can see the photo of a tweeded, bearded, younger version of himself standing over Joe Frazier at a boxing gym in Philadelphia, in 1971, a picture taken weeks before the latter beat Muhammad Ali in The Fight of the Century. This brings us to Norman Mailer. There were plans, but the two never boxed each other. “I just didn’t want to flatten my nose,” Donleavy says.

I tour the house, whose peeling walls are hung with many pictures painted by Donleavy, and several other paintings of him. There have been about twenty gallery shows of Donleavy’s work, in Dublin, London, and New York. Framed pictures are stacked against the wall, sometimes five deep, in the corridors and nooks of the first floor. Deborah takes me upstairs.

“Nobody’s allowed in the bedroom without J.P.,” she tells me, as I notice the Do Not Enter sign. “Not even the cleaning lady, and she’s been here longer than I have.” When I return to the kitchen, I see that Donleavy has put on a funny pink bucket hat. He tells me he never allowed any changes to his manuscripts, nor is he particularly inviting of second readers or the like. I am curious how he knew when “The Ginger Man” was complete.

“I knew I was finished when I had enough pages following one another to look like a book,” he says. That book has sold over forty-five million copies and has never gone out of print. It is also on the Modern Library’s list of the best one hundred novels of the twentieth century, in ninety-ninth place, between James Cain’s “The Postman Always Rings Twice” and Booth Tarkington’s “The Magnificent Ambersons.”

In the large living room, on a piano, there’s a bust of James Joyce, looking out at an enclosed but not exactly manicured garden. “His father had to come out to this area and do some sort of business, and Joyce came along and actually came to this house,” Donleavy had told me. In “Stephen Hero,” Joyce describes walking through the front entrance and seeing the garden. Donleavy says he didn’t know this when he bought the house.

Elsewhere in the living room is a banker’s box marked “Dog of the Seventeenth Floor.” This is the current manuscript, unfinished. In the study are the finished ones: a bookshelf measuring about twenty by eight is full of books, and nearly all of them are various editions of Donleavy’s own novels and plays, plus other oddities he’s authored, such as the part-travel essay, part-autobiography called “J.P. Donleavy’s Ireland: In All Her Sins and in Some of Her Graces.”

When the pastries are gone and the tea is cold, Donleavy offers to accompany me to my rental car, a tiny gold Micra. It looks preposterous in front of the manor, and the sight seems to delight him. He is effusive about it. “It does the job,” I say. “What a funny thing,” Donleavy laughs. “Yes, that would be a good title for one’s memoir.” For one’s memoir, perhaps, but not for Donleavy’s, I think, as I watch him grow smaller in the side-view mirror of my car.