Yet after reigning over Britain for longer than most of her subjects have been alive, Queen Elizabeth II is the country's "most familiar enigma," in the words of one TV presenter.
Yes, the white-haired 86-year-old keeps up a grueling schedule of public appearances that would test someone half her age, especially during this season of celebration of her Diamond Jubilee, marking 60 years on the throne. This weekend, the queen kicks off a four-day extravaganza by going to the races Saturday and cruising down the Thames on Sunday at the head of a flotilla of up to 1,000 boats.
Photos: Queen Elizabeth II through the years
But a certain regal aloofness, a touch of otherworldliness that lends some credence to the title "Your Majesty," is a crucial component of her long success as monarch, some say.
"You do need a little bit of mystique," said Sue Daws, 52, who lives in northern Wales.
Note to heirs: You might want to work on that.
Elizabeth is the last member of the House of Windsor for whom royalty and celebrity don't overlap, or at least not by much, a distinction many observers credit with helping to preserve the monarchy's appeal.
Her discretion and dignity are in marked contrast to the behavior of her four children. Unlike them, she doesn't submit to tell-all interviews about unhappy marriages, hasn't had details of her sex life laid bare in the tabloids, didn't take part (not even for charity) in an embarrassing game show called "The Grand Knockout" in 1987 (as did Princess Anne and Princes Andrew and Edward, in a moment that for many Britons represented "the breaking of royalty's magic spell," as one writer later put it).
Just last month, viewers of the BBC in Scotland switched on the TV to find their future king, Prince Charles, giving the daily weather report in his immaculately clipped tones, a surprise appearance that's become a minor hit on YouTube. ("Potential for a few flurries over Balmoral [Castle]," he said of his family's Scottish quarters, then stopped and asked, "Who the hell wrote this script?")
Although it was a good-natured and generally well-received cameo, a spot of hammy humor from an often stuffy heir apparent, no one can possibly imagine the woman he calls "Mama" doing the same thing.
"The queen has always avoided what she calls stunts," said Robert Lacey, author of the just-published "The Queen: A Life in Brief." "The monarchy has got to distinguish itself from other aspects of British public life."
Part of Elizabeth's aura of solemn reserve is natural to her temperament and her generation, with its harrowing experience of world war and its innate aversion to making a spectacle. Lacey notes that she grew up in the era depicted in the movie "The King's Speech" — the king in question was her father — when mass media were still novelties and engaging them wasn't automatically part of the British sovereign's job description.
But some of the queen's detached grandeur is carefully cultivated and maintained.
There are countless biographies, but no autobiography. Her public comments are polite, unexceptionable and totally unrevealing. Everyone knows about her love of dogs and horses, but only those closest to her have any real inkling of the thoughts beneath the diamond tiaras and behind the guarded smile.
"She is the most portrayed individual in history, more than anyone you can think of — popes, prime ministers, presidents," said Paul Moorhouse, curator of a new exhibition, "The Queen: Art & Image," at the National Portrait Gallery here in London. "The paradox is, what does anyone know about her? Her opinions are a closed book. Nobody but her intimate family knows what she thinks."
Royal protocol certainly helps perpetuate the idea of a person set above and apart. At meals, guests are supposed to stop eating when the queen does. (It's said she keeps a final morsel on her plate to roll around so that others can keep noshing without embarrassment.) Even her family members have to rise when she enters.
"Whenever Granny walks into a room, everyone stands up, stops and just kind of watches her," her granddaughter Princess Eugenie told the BBC recently.
"I find that incredible. I kind of go, 'Ah,'" Eugenie said, feigning a gasp.
But with that air of exaltedness comes a delicate juggling act, royal watchers and historians say.
Though fundamentally unknowable, the queen can't be too distant and unapproachable. At the same time, she must somehow give the impression of being close to her people. Her private motto is, "I have to be seen to be believed."
"In modern times, the British monarchy has been an accommodation of two opposing factors. One is a sense of aloofness or majesty or royalty, and the other is the opposite, the sense of being almost an ordinary human being," said Michael Billig, a social scientist at Loughborough University. "If they don't get that balance right, they're likely to be unpopular."
Hence her many appearances opening hospitals, christening ships and inspecting military regiments, always in her trademark hat and pearls. In fact, when Britons are asked to explain their admiration of the queen, many talk about how diligent she is in dispatching her duties, how the "old girl" soldiers on despite her age. She is only the second British monarch to reach 60 years on the throne and celebrate a diamond jubilee; the first was her great-great-grandmother Victoria, 115 years ago.
"The queen has become popular because there she is, an elderly woman who's still working," Billig said. "That's a very down-to-earth assessment."
Popular is right: The left-wing Guardian, which is staunchly republican on its editorial pages, nonetheless published a front-page story last month on the record popularity that "brand Windsor" currently enjoys.
The queen consistently ranks as the most beloved representative of that brand; thousands of well-wishers greet her wherever she goes, eager for some sort of connection. The question is how well the royal family will be able to sustain that semi-magical appeal once she's gone.
Many of the queen's numerous progeny maintain just as taxing a regimen of charity work, royal "walkabouts" and other ornamental appearances.
Yet unlike her, they have all had the veil of mystery stripped away to some degree, often in the most unflattering of ways. Prince Charles' recorded phone conversation with his then-mistress, now-wife, Camilla Parker-Bowles, still induces winces more than 20 years later, particularly the royal references to feminine hygiene products.
That kind of exposure might be in keeping with modern celebrity, but doesn't necessarily suit a centuries-old monarchy.
"When [the queen] goes, it'll completely change. It'll turn the corner," said Daws of north Wales. "If you look now, they're very touchy-feely, whereas with her, there's this boundary around her."
Author Lacey said that even the regular-bloke-ish Prince William, the second in line whose wedding to Kate Middleton a year ago set off a breathless bout of royal mania, may discover to his regret later that it's possible for the monarchy to be too of-the-people.
"He and Kate are a glamorous couple who chose Los Angeles, of all places, as somewhere to stop on their first foreign tour. Will people feel the same about them in 20 years' time, or will they not feel too much familiarity?" Lacey said.
"That's the risk, or the challenge, that lies ahead for the monarchy: how to maintain its mystique in an age of popular access," Lacey said. "It's what distinguishes royal celebrities from all others."