LONDON — The theme of the walking tour was the forthcoming royal wedding, but the object of the group’s obsession was Kate Middleton, the royal bride. In Mayfair, the guide paused at the next important landmark: the Jigsaw store on Dover Street.

“Kate’s struggle to hold down a job since graduating has reportedly earned the displeasure of the queen,” declared the guide, Hana Umezawa, as earnestly as if she were explaining the Spanish Armada. “The closest Kate has come to having a regular job was when she worked at Jigsaw as a part-time assistant accessories buyer from 2006 to 2007.”

What do you say about a young woman who went to college, fell in love and became engaged? With Kate and Prince William’s wedding a little more than a week away, the chances of the public — that is, us — learning anything new about Miss Middleton before she turns into a princess (or a duchess, depending on which title she takes) are zero.

Now 29, she has formally spoken to the press only on the day she and William announced their engagement and submitted to a gentle sprinkling of softball questions. She appears to have spent a lifetime avoiding unseemly episodes.

“It’s absolutely extraordinary — people do comment and talk about what she’s like, but we know almost nothing about her,” said Valentine Low, who writes about the royal family for The Times of London. “She’s a blank cipher. She’s existed in this funny little bubble for the past nine years, and they’ve done a brilliant job of controlling the flow of information, just letting out enough for us to feel that we’re getting something.”

Miss Middleton is a rarity in this era of lives played out in public: a megacelebrity who has never been on a reality show, has no Facebook page, does not tweet and is not preparing to reveal all in a memoir. She is like an old-time Hollywood star, full of mystery, a canvas onto which the world can project its fantasies.

If Diana, Princess of Wales, was an aristocrat with a common touch, Kate Middleton is a commoner who has triumphed among aristocrats. But just as it did with Diana, a public voracious for new juicy details will have to make do with recycled scraps from a banquet that has long since been served and cleared away.

How she grew up in Bucklebury, Berkshire, with two loving and good-looking parents who met while working at British Airways, he as a flight dispatcher and she as a flight attendant.

How she has a brother, James, who has largely stayed out of the limelight, and a sister, Pippa, who largely hasn’t.

How her mother, Carole, has ancestors who were miners, and how Carole left behind her working-class roots when she and Kate’s father, Michael, founded a successful Internet business that sells party accessories. How their newfound wealth allowed them to move into a grand country house and to send Kate to Marlborough College, an elite boarding school, where she excelled at sports but not, unfortunately, at misbehaving.

There is some debate over how early Miss Middleton became aware of Prince William as a potential husband. In his book “William and Kate: A Royal Love Story,” Christopher Andersen describes her as having spent her teen years fantasizing about William, poring over news articles about him, even putting images of him up on her wall.

Asked in their engagement interview whether she in fact did display a poster of William in her dorm room, Kate grinned and said, “He wishes.” (She added: “I had the Levi’s guy on my wall — not a picture of William. Sorry.”)

Their courtship at the University of St. Andrews, where both were students, has been told in endless articles, books and television specials. But only a few insiders know if the episode that is supposed to have ignited the royal passion — when Kate appeared at a fashion show in a see-through dress and William uttered the prosaic but fateful words, “Wow! Kate’s hot!” — really happened that way.

The two, who by all accounts have an easy and joking relationship, lived together in a group house, first as friends and then as a couple. He introduced her to his family and hung out with hers. When he wavered about whether college was right for him, she persuaded him to stay.

They graduated. He joined the military. She worked part time for Jigsaw, and part time for her parents. She stopped working. They went to a lot of nightclubs.

Another key spot on the royal wedding tour was Mahiki, a Polynesian-themed club that is a known drinking location for William, a (possibly reformed) known drinker.

Here, Ms. Umezawa related, William’s friends were believed “to treat Kate unkindly by making derogatory references to her middle-class background,” including muttering the flight-attendant phrase “doors to manual” when they saw her. It was also here, she said, that William came to celebrate after he and Kate (briefly) broke up in 2007, leaping onto a table, yelling “I’m free,” and amassing an $18,000 bar bill in less than a week.

Since they’ve reconciled — “Kate, by her aloof behavior, gained the upper hand,” Ms. Umezawa explained — they have lived together in Anglesey, Wales, where William works as a search-and-rescue pilot for the Royal Air Force. They reportedly do their own shopping and possibly even their own cleaning.

“Kate has played it beautifully,” said Kate Reardon, the editor of Tatler magazine. “She appears to be modest and conservative and un-showoffy and everything that we would love her to be.”

In her last days being single, Miss Middleton appeared to have gone into lockdown. However, she was spotted shopping in London this week. But the more she stays out of the limelight, the more fevered and, in a way, paltry, the speculation becomes. She designed her own wedding dress! No, she had three competing dresses made by three competing designers! No, she has one dress, and it is locked in a vault in Clarence House (home of Prince Charles)! She is worryingly thin; how will the dress fit?

None of this will be cleared up until the big day. Even Hello!, a magazine that can turn the rustling of a breeze near a royal palace into a news story, has had to make do with less than usual.

“Kate’s big wedding secret revealed,” it promised on the cover of last week’s issue. Inside it disclosed, citing unnamed sources, that Miss Middleton would not hire a professional makeup artist for her wedding but would apply her own.

That seems highly unlikely, given that a television and Internet audience of approximately 2.5 billion people will be on hand next Friday to critique her makeup job, along with everything else about her. And think of the wedding photos.

But who knows? The palace had no comment.