M Neilson, Getty Images

It's the stuff of royal legend: A young university coed (Kate Middleton) catwalks past a handsome prince (William) in a completely sheer slip-dress.

The young prince-on-campus cranes his neck to get a glimpse of the brunette beauty, and their fairy-tale romance begins.

The $45 silk lingerie-dress famously worn by Middleton and created by young design student Charlotte Todd in 2000 is now a royal artifact worth at least $15,000, British auctioneer Greasbys told the Daily Mail.

The auction house predicts its value could exceed $160,000 when Middleton becomes a princess following her April 29 wedding.

Todd, who now works at an aquarium, recently retrieved the stashed dress from her mother's closet, where it's been stored since the fateful fashion show.

Todd told the Daily Mail there's little chance she'll part with the dress. "If it hadn't been see-through, William might not have noticed her. I definitely think it played a part in the royal love story," she said.

Todd made the dress from black and gold silks for a design school project dubbed "the art of seduction." It took her about a week to knit the two fabrics together and add blue ribbon trim, she told the paper.

In 2002, St. Andrew's University, where both Middleton and the prince were students, asked to borrow the racy frock for a fundraiser fashion show. Middleton was dating someone else when she strutted past the prince, her hair set off by a slender side braid and her black undies and bandeau bra-top clearly visible.

Todd said the piece was actually a skirt, but Middleton opted to wear it as a dress.

"Kate was a great clothes horse to show off my design," Todd recalled. "Her body was the exact right shape to pull it off."

As for offers to part with it, Todd told the newspaper, "The only person I would probably give it to is her, maybe in exchange for a wedding invitation."

Todd also sketched up her own version of a wedding dress for the queen-to-be, which she shared with a U.K. newswire service, but she's stepping on a few designer trains with that offer.

Read about the designer who British oddsmakers predict is a serious contender for the role of royal wedding dressmaker.

Where did Middleton get her great style? Perhaps her parents had something to do with it. Did you know they have a party company?

And here's the scoop on the designer behind-the-seams of Middleton's electric-blue engagement announcement dress.

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