Any vague foreboding about the island of Mustique—any fear of being cold-shouldered by wintering Anglo-Saxon aristos wearing pastel prints and the flush of gin martinis—evaporates as soon as the slip of a runway comes into view. On the airport’s terrace stands a surprise greeting party, the arms of well-wishers flapping like the flags that poke up through the terminal’s thatched roof. Hellos and goodbyes are big on the island, especially the latter: Being waved off Mustique—or, depending on how spirited the company is, mooned off it—is one of many old traditions, as any island diehard will tell you.

“You could call this place a healthy addiction,” Jeannette Cadet says a few nights later. I run into her at the beach bar at the Cotton House, the hotel that Colin Tennant, later Lord Glenconner, established a decade after he bought the Caribbean island, part of St. Vincent and the Grenadines, in 1958 for 45,000 pounds (around $126,000 at the time), assuring his wife that it would be cheaper to spend the winters there than to heat the family castle in Scotland. Cadet, a St. Vincentian by birth, is Mustique’s unofficial social chair, known to all, and all-knowing. (I’m told she reviews the manifests of every incoming flight.) It was Cadet who secured L’Ansecoy, a simple ­cliffside cottage belonging to Maguy Le Coze, owner of New York’s Le Bernardin restaurant, for the art dealer Tim Jefferies and his wife, the Swedish model Malin Johansson. That couple have just arrived at the bar, and immediately they greet the London girl-about-town Amanda Sheppard, who nurses a rum punch. Sheppard is staying at Blackstone, a house that used to belong to the Canadian country singer Shania Twain. Nearby, Belle Robinson, a cofounder of the British clothing chain Jigsaw and owner of a pair of Italianate villas overlooking Macaroni Beach, sits with her daughter Christy; Ricky Hilfiger, Tommy’s son, regales a few friends visiting from Los Angeles; and the artist Marc Quinn watches as his girlfriend, Jenny Bastet, kicks up the cool evening sand with her infinite legs. Everyone knows one another, at least a little, and strangers are absorbed effortlessly. There is always the sense on self-selecting Mustique that if you’re here at all, you’re fine.

Despite this low hum of glamour, the island’s initial impression is one of enforced wildness, unchanged since the days when this deeply green volcanic outcropping provided Princess Margaret, Queen Elizabeth’s sybaritic sister, with a refuge from monarchic manners and the world’s scrutiny. There are no street signs, traffic lights, ATMs, or golf courses. The dress code calls for bare feet. If one of the island’s ubiquitous red-footed tortoises steps into the road to begin a slow crossing, one waits reverently in one’s “mule,” the golf cart–ATV hybrid that serves as the main mode of transportation. This quaintness is precisely the point. Mustique jealously guards what one resident describes as “the illusion of simplicity.” It has no deep dock for a megayacht and no place to land a private plane, which supposedly sufficed to steer the Russian billionaire Roman Abramovich over to St. Barths.

“In St. Barths, they’ve turned their island into Saint-Tropez,” the musician Bryan Adams says. “Here, it’s the opposite. We have a little boutique, a little restaurant. That’s the whole idea.” Adams lives in a wind-lashed stone villa once owned by the Venezuelan tycoon Hans Neumann and designed by the British set decorator Oliver Messel, who had a major second act as the creator of a Caribbean colonial style of architecture, on stunning display here and on Barbados. On a hill above an isthmus, Adams grows his own pineapples, papayas, avocados, and pumpkins. He is a passionate preservationist and has been involved in the restoration of the island’s coral reefs. “We’re the most environmentally forward island in the Caribbean,” he says.

Adams is not the only rock-star resident. Mick Jagger owns a Japanese-style house down the beach. The late David Bowie was inspired to buy his own place after staying with Jagger. Somehow, no architectural trend is out of context here, where everything is a kind of folly. French chateaux, Moorish pavilions, futuristic fantasias, and antebellum plantations cohabit with the hills, beaches, and cliffs. During my visit, there is some excited chatter about the 25-foot television that the Canadian billionaire Lawrence Stroll apparently is erecting on the beach outside his substantial enclosure, called the Great House (once Tennant’s island home). “There’s no taste police here, and there never should be,” says Dora Loewenstein, a London event planner and the daughter of Prince Rupert Loewenstein, the longtime business manager for the Rolling Stones. “Whether you like it or not, it’s always interesting.”

Loewenstein has been coming to Mustique for nearly 40 years, and she serves as chair of the board of the Mustique Company, the island’s cooperative-like governing body (on Mustique, homeowners are shareholders). “When I first came, everybody did everything together,” she remembers. “If there were drinks, everybody was there. Lunch, the same. It was this great, endless merry-go-round. And then there was a bit of an awkward phase when it got too big for everyone to go to everything. Finally, it got just big enough that people could do their own thing.” These days, Loewenstein presides over Zinnia, another old Messel house, with her husband, the interior designer and Italian count Manfredi della Gherardesca. (Some readers may recall della Gherardesca’s 13th-century forebear, Ugolino, buried up to his neck in ice in Dante’s Inferno.) Previously dubbed Banana Bread, the cottage was a wreck when Loewenstein’s parents bought it in 1996. Dora’s mother, Princess Josephine, commissioned its sensational trompe l’oeil murals, aware that no art survives the salt air. The house is now among the island’s splendid embodiments of Messel’s spindly neoclassicism, with white columns, intricate gingerbread detailing, and a lime-colored clapboard exterior. On the day I show up, the model Lady Jean Campbell, the daughter of Loewenstein’s friend Lady Isabella Cawdor, sits on the veranda in a white caftan scrolling through her iPhone, a single long blonde braid cascading down her back.

On the northwestern edge of the island stand Messel’s earliest Mustique creations, Clonsilla and Phibblestown, named for villages in Ireland by their original owner, Lady Honor Guinness. An heiress to the brewing fortune, Guinness was the first to buy a plot of land from Tennant. “As a respectable lady, she made the island less scary,” says her granddaughter, the Honorable Georgia Fanshawe. Fanshawe now owns Clonsilla and was part of the first generation of children on the island, those who had their birthday parties thrown by Tennant and who established the tradition of naked pool hopping, which has lately fallen out of favor. Clonsilla, with its flattened-arch windows, serves as an unofficial Messel museum. A crumbling stone Messel mask dribbles water into a lily pond out front; inside, his whimsical mermaid paintings adorn the white walls that he insisted on. “These houses weren’t meant to be grand,” Fanshawe says. “In fact, it was very basic at first. There were power cuts constantly. Thankfully, there was a Swedish electrician, who was always drunk, whom you could summon.”

The houses, tasteful or tacky, quiet or brash, are island characters in their own right. The meaning is perfectly clear, for example, when someone says that Windsong has invited Hibiscus up for lunch. Roughly half of the 104 houses are still owned by Brits, and a certain Englishness prevails: Dinner (roast beef is probably on the menu) is at 8:30 p.m., unless a televised cricket match between England and the West Indies pushes things back. Nearly everyone comes to Tuesday-evening cocktails in the Cotton House—the island’s only hotel—to see who’s flown in. The crowd does have its seasonal rhythms: New Year’s and Easter tend to draw homeowners, especially the English. Midwinter lures a New York crowd, and the summer months fill up with French and Italians. The Duke and Duchess of Cambridge have become regular visitors; fortunately for them, the paparazzi have not. In the days of Princess Margaret, a boat from the MI5 fleet patrolled the shores to guard against interlopers. More recently, when a visitor claiming to be a birdwatcher arrived with a lot of photo equipment, the island’s security crew looked at his film and, upon discovering his ruse, locked him in the Cotton House before sending him home on the next flight.

Tennant hoped that Mustique would be an escape for friends like Princess Margaret, who was addicted to parlor games and loved nothing more than a simple picnic. Though the island had a moment of Dynasty-era flash, when caviar was served on the beach by liveried butlers on silver and fine china, a more pared-back style is once again the fashion. Picnics under the large thatched-roof palapas remain hugely popular, and they can still be lavish, like the one that Katie Cecil and her husband, Mark Cecil, who runs a Swiss hedge fund, stage on Lagoon Beach during my visit. The hut is festooned with bunting in a Mustique-pink toile de Jouy, designed by Lotty Bunbury, the local doctor’s wife and owner of the Pink House shop. The Cotton House’s chef lays out a surf-and-turf of grilled Caribbean lobsters and barbecued pork ribs. “When we first started coming here, 17 years ago, it was fish and boiled cabbage,” Katie remembers. “And if there was a Christmas storm, lunch was served under the table. We carried on—very British.” The Cecils’ daughters, Lottie and Yumyum, decide to sit out the hands-behind-the-back pie-eating contest. Little Coco Jefferies loses due to an excess of manners but vows to beat the boys next time.

“It’s not called Mustique for nothing,” says Katrin Bellinger, referring to the fact that the island’s name is a bastardization of the French for “mosquito.” “Tennant’s wife, Anne, was bitten on her bum through every hole in the rattan furniture.” Bellinger is a well-known dealer in Old Master prints and drawings, and a beauty who was photographed by Slim Aarons when she was a teenager. Her husband, Christoph Henkel, is a London-based German entrepreneur whose grandfather made a fortune with laundry detergent. They discovered Mustique 20 years ago on their honeymoon and now live at Rutland Hill, designed in 1981 by the Swedish architect Arne Hasselqvist, a frequent collaborator of Messel’s. The house resembles a series of pavilions, a classic Messel effect achieved by giving contiguous rooms their own discrete roofs. Bellinger’s days often begin with yoga on the beach and proceed to the island’s brief list of recreations: a swim, a hike, tennis, maybe a drink at the beach bar. “You feel absolutely no social pressure here,” she says. “You don’t put on your Hervé Léger dress and your high heels on ­Mustique. There’s no place for them.”

That’s not to say that the island lacks glamorous occasions. Of course, Tennant’s nocturnal entertainments were legendary: local boys wearing nothing but a single coconut shell, a forest of trees painted pink, Bianca Jagger dressed as Scarlett O’Hara. These days, there may be no spectacle quite like that of Daphne Guinness swimming on Gelliceaux Beach up to the Belgian financier Pierre Lagrange’s 007-style bamboo house in a silver deep-V maillot, diamonds, and waterproof headphones. Above this intensely turquoise scoop of sea, the Swiss art collector and philanthropist Maja Hoffmann occupies a pair of villas, Gelliceaux and Neubau Lagoon House, the latter an ultramodern array of cantilevered concrete-and-steel structures, with cascading pools designed by the Venetian-born New York architect ­Raffaella Bortoluzzi. Hoffmann has been coming to Mustique for more than two decades and remembers the impression that the island first made on her. “I didn’t wear shoes for three days,” she says. “That’s what got me in the end.” For years she stayed at Plantation House, on an adjacent high hill; Tom Ford often rents it. “In the beginning, you say, ‘My God, what am I going to do here?’ But very fast you get into this repetitive rhythm. Yes, the prices have gone up, so you start to get a single category of people. But the routine is still deeply relaxing, even if you sometimes feel that there are too many parties.”

Decades ago, as the island began to swell with revelers, Tennant asked his bartender at the Cotton House, Basil Charles, to help him build a tavern in the quiet fisherman’s harbor of Britannia Bay. Charles was the only man who ever asked Tennant how he took his rum and coke. (The answer: a long shot of white Bacardi, a dash of Coca-Cola, a pair of ice cubes.) Thus began a long friendship, and, eventually, Basil’s Bar became an institution. Princess Margaret often began her evenings there with a whiskey, and, to this day, few visitors to the island skip Jump Up, the Wednesday-night party at which Charles serves roast suckling pig and a cover band takes the stage. Charles was awarded an Order of the British Empire in 2005, and a few years later went to Buckingham Palace, along with Jeannette Cadet, for Prince William and Kate Middleton’s wedding.

“This island is the last thing you would expect it to be,” Charles says. “It’s a family. You look out for people, no matter who they are, and they look out for you.”

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