David Hockney always claims that he has never sought out his assistants. "They have found me," he jokes. I found Hockney in September 1984 in Chicago. He was then 47, still sporting the shock of platinum hair that became his trademark in the early 1960s, when he burst onto the international art scene. (The natural brunet thought, "If blonds have more fun, then why not give it a go?") I was about to turn 25 and was earning my living working at Chicago's Museum of Contemporary Art, which was then presenting a Hockney exhibition. About an hour before Hockney was to arrive at the museum for a press walk-through of the show, I got a call saying that movie legend Cary Grant and his wife, Barbara, would be joining the artist on the tour. The unlikely friends had met a year before at a book signing in Beverly Hills when Barbara asked Hockney to sign one "for Cary." Hockney, always a terrible speller, asked, "As in Cary Grant?" Barbara replied, "Yes, he's my husband." A lifelong movie fan, Hockney laughed and said, "Well, if it's for Cary Grant, then I'll make a drawing!" He quickly drew a series of dancing Punchinellos reminiscent of his costume designs for the Metropolitan Opera's 1981 production of Maurice Ravel's L'Enfant et les Sortilèges. Fast-forward to that night in Chicago, when I had the task of helping Hockney with his book signing. We fell into a conversation about Picasso and cubism that continued when we all went out for dinner after the opening. The next morning, when I arrived at work, there was a copy of his latest book, Cameraworks, addressed to "Charles the Cubist." Less than a year later, I moved to Los Angeles to work for him. (As for Cary Grant, he and Hockney remained friendly until his death in 1986.) In the past three decades, I have served as Hockney's assistant, a friend, a sitter at various times for portraits, a curator, a travel companion, and, most important, a devoted follower of his work. His 2005 Self-Portrait with Charlie, now in the collection of the National Portrait Gallery in London, captures me as I watch him paint his own self-portrait. Looking back, I realize that I have spent most of my adult life trying to keep up with this most original and provocative man. It's no easy feat: At 74, Hockney is showing no signs of slowing down. This January, London's Royal Academy of Arts will be launching "David Hockney: A Bigger Picture," a five-decade survey of Hockney's recurring interest in landscapes, from his early paintings to experimental photocollages from the 1980s to recent large-scale, multicanvas compositions and films of his native Yorkshire, England. Of course, much of it is very recent work. In true Hockney style, he views this show as proposing a new way of perceiving the world, without the limitations of linear perspective. "I think I am seeing more clearly now than ever," he told me recently. "We're on a roll." Hockney is extraordinarily prolific, working in all media, including drawings, prints, photographs, film, the iPad, costumes and sets for opera and ballet, and art-history texts published at a pace that would make an academic shudder, but his fans return again and again to his paintings. The recent death of his close friend Lucian Freud has led most of the press to ask if Hockney is now Britain's greatest living painter. Hockney shrugs off such honorifics, placing little stock in the accolades he has been showered with in his career. "You wouldn't call Picasso an award-winning artist, would you?" he says, laughing. He also quietly turned down a knighthood in 1990. "I thought as I was living in California [at the time], it didn't seem appropriate," he says. Despite that decision, Hockney has been a weekend guest of Queen Elizabeth II at Windsor Castle and Prince Charles at Highgrove House. Their royal highnesses have even allowed the unrepentant smoker to light up during his visits with them. (Hockney is famously a vocal advocate of smoker's rights, passionately writing letters to newspapers and magazines, countering the claims of what he calls the "health police." "They've gone too far," he says, pointing out, "You can't have a smoke-free bohemia.") As for his royal hosts, he notes with good humor that their reaction to his habit is self-evident: "I haven't been invited back." He has, however, moved back to his homeland in recent years, trading his Los Angeles residence for the seaside resort of Bridlington in Yorkshire, where he's lived since 2005 and works on his films as well as the large multipanel paintings that he creates en plein air. In fact, his largest work ever, 2007's Bigger Trees Near Warter, a 15-by-40-foot painting made up of a staggering 50 canvases, was constructed thusly. But his first love will always be Southern California. "I am simply working on location," he jokes of his current life. Ever since his first visit to the West Coast in 1964, Hockney has been captivated by California's sun, colors, vast spaces, gorgeous people, and, of course, swimming pools. Early on, he became friends with novelist Christopher Isherwood, who, as he recalls, told him, "Oh, David, we've so much in common; we love California, we love American boys, and we're both from the north of England." From the very beginning, America flung open its arms to Hockney, whose cocktail of charm and talent was an instant hit. And after spending much of the '60s and '70s bouncing between New York, Los Angeles, Paris, and London, Hockney made the move to California in 1978. He bought a house in the Hollywood Hills once owned by actor Anthony Perkins and his wife, Berry Berenson, and built a studio on what had been a paddle-tennis court. The gardens became Hockney's own version of Claude Monet's Giverny—the inspiration for hundreds of iconic environmental works of his home and gardens. By the time I was working for Hockney, his favorite haunts were the old Spago—where he drove Wolfgang Puck mad by always opting for the quieter "Siberia" in the back—Chasen's, the old Bistro Garden, and the now-shuttered Japanese standby Imperial Gardens on Sunset Boulevard. But New York was still a regular stop to visit friends like Andy Warhol, who he met in 1963. The two artists always kept in contact over the years, and each did the other's portrait. In 1987, the year he died, Warhol asked Hockney to create a cover for his Interview magazine. We spent an afternoon with Warhol at the Factory, and Warhol told us he was going to have his gallbladder removed the next week. We flew back to Los Angeles only to hear the news that Warhol had died two days after the surgery. That April, Hockney attended the memorial service at New York's St. Patrick's Cathedral, and that night, looking over the Manhattan skyline, he said, "Now that Andy is gone, how will people know what the hot spot is each night? Andy always knew." Hockney didn't lose touch with London, where designer Ossie Clark was one of his closest friends during the '60s and '70s. Hockney was the best man at his 1969 wedding to textile designer Celia Birtwell. He immortalized the couple in the iconic painting Mr. and Mrs. Clark and Percy, portraying them at their Notting Hill home. (Clark's penchant for nightclubbing and his resulting 4:00 P.M. wake-up time endangered their daytime sittings, recalls Hockney in Birtwell's recent self-titled memoir. "I heard Celia say to him one day, 'Now, you come straight home after that club.'") And though the marriage didn't last, Birtwell became one of Hockney's closest confidantes, a frequent partner in crime, and an artistic muse. The two bohemians became successful—and just barely respectable—enough that they eventually earned an introduction to the queen mother. The late arts patron Sheridan Dufferin tried in vain to teach them the better points of etiquette before the royal arrival. Hockney still laughs about the theatrical deep curtsy Birtwell performed when the queen mother entered the room. "We have a very similar sense of humor," says Birtwell, saying they both adore watching Laurel & Hardy movies. The only time the mood is solemn is when Hockney is at work. "You don't say anything unless he speaks first," she says of a typical portrait sitting. "He's very serious, and you can see the intense concentration in his eyes. He also pulls the most extraordinary faces as he fights to get the image exactly right." Other designers have derived as much inspiration from Hockney as he has from them. He has always been a natty dresser, and his ensembles consist of the ever-present round spectacles, blond hair (now gray), sharply tailored suits, and color-blocked pieces in rich purples and bright blues. He shared a deep admiration and mutual friendship with the late Yves Saint Laurent, who paid homage to him in his Spring 1988 ready-to-wear show. And designer Zandra Rhodes, a contemporary of Hockney's at London's Royal College of Art, says he was the catalyst who drove her to abandon art for fashion. But despite the sparklingly glamorous social life that from the outside he appeared to lead—from walking the red carpet with Anjelica Huston at the Vanity Fair Oscar party to hanging out with intellectual greats like the late William S. Burroughs and Allen Ginsberg—it is really all an illusion. "As for the world of fashion and celebrity, I have the usual interest in the human comedy, but the problems of depiction absorb me more," Hockney says. He's currently happiest living the quiet country life in Yorkshire, where, he says, "I like visitors mdash; just not that many." Lately, he has been focusing on filming the local landscape, where neighbors can find him and his assistants driving down country roads in all weather in a Jeep outfitted with nine high-definition video cameras. "Most of the local people think this is just a road from A to B," he told me on one recent dawn outing. But for him, it's a veritable artistic medium. And he enjoys the freedom afforded by the isolation: "If this was in America, we'd have had to get all kinds of legal clearances to make these films. Nobody bothers us here." The film work is a natural continuation of Hockney's fascination with technology, which began in the early '80s, when he started experimenting with photocollages using Polaroids and 35mm prints, followed by photocopies and "fax art." (He once faxed an entire exhibition from his Los Angeles studio to São Paulo, Brazil.) The results of this latest project are such that viewers can experience a journey down a country road on multiple screens, with spring depicted on one side and fall on the opposite side. "By putting the separate perspectives there, the eye is forced to scan. Not everything can be seen at once," Hockney explains. "This seems to make the outside edge less important—almost taking it away." It's his attempt to break through the limitations of the photograph and the traditional Western perspective intrinsic to the camera. "All film directors, even the ones using 3-D today, want you to look at what they chose." Instead, Hockney adds, "Our way gives the choice back to the viewer, hence it seems to me a greater possibility for new narratives." His interest in technology also led him to a new medium, discovered when he first purchased an iPhone. Using the Brushes app, first on the iPhone and subsequently on the iPad, he has created more than a thousand drawings, which became the subject of the traveling exhibition I curated, "David Hockney: Fleurs Frãiches," currently on view at the Royal Ontario Museum in Toronto. He makes iPhone flowers bloom and sends them to his friends "so they get fresh flowers every morning," he told Martin Gayford, author of a new book on Hockney, A Bigger Message. "I can also send [the drawings] to 15 or 20 people, who get them immediately." But for all his generosity, Hockney, like his idol Picasso, has kept a large quantity of his best work for himself. The scarcity of available Hockneys is reflected in the market: His paintings, works on paper, and photocollages are now drawing record prices. His 1966—67 painting Beverly Hills Housewife sold for $7.9 million in 2009. But none of that matters much to Hockney. "There is only now" is a favorite saying. And what's his key to a good life, Hockney-style? "Laugh a lot. It clears the lungs."