See Princess Diana's Secret 'Spare' Wedding Dress in Never-Before-Seen Photo

Designer Elizabeth Emanuel described Diana's backup bridal ensemble as "similar in certain respects and both had the big skirt, but everything else was different"

Princess Diana was prepared for every style possibility for her walk down the aisle — including having a second backup wedding dress!

Although sketches of the extra bridal gown have been revealed before, Elizabeth Emanuel shared a never-before-seen photo of the "spare" dress with Hello! magazine. In the snap, a woman is seen working on the ensemble as it is laid on a table.

Elizabeth, who created the royal's wedding dress alongside her ex-husband David, told the outlet, "The spare wedding gown was made just in case the secret of the real dress ever got out. Fortunately, it was never used. The dress was made in pale ivory silk taffeta with embroidered scalloped details on the hem and sleeves. Tiny pearls were sewn on the bodice."

"People always ask you what it was like," she added. "It was similar in certain respects and both had the big skirt, but everything else was different."

Related: The Best Royal Wedding Dresses of All Time

While Princess Diana tied the knot with the future King Charles in July 1981 in a dress featuring voluminous sleeves, the extra ensemble featured more fitted sleeves. The V-necklines and arm openings on both featured similar ruffle details, with the backup option slightly more subdued.

The dress, which was never fully completed, was created in case the design leaked to the press before the big day. The designers even went as far as to create "false trails" by putting the wrong fabrics in the garbage for the press to find, Royal Style in the Making exhibit curator Matthew Storey previously told PEOPLE.

Princess Diana never even tried on the second dress — and its current whereabouts are unknown, even by the designer.

"I don't know where it went. It just disappeared," Elizabeth told Hello!

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Princess Diana made her wedding vows at St. Paul's Cathedral in an ivory and silk taffeta gown with antique lace that was once worn by Queen Mary. Its train trailed 25 feet behind her — the longest train ever worn by a British royal bride — and had to be folded like a bedsheet to fit into the carriage.

The train was so cumbersome that Diana told bridesmaid India Hicks to do her "best" while carrying it down the aisle. "We knew what that meant: If we pulled too much, straightening the material, her tiara and veil would slip," Hicks told Harper's Bazaar in 2018. "But if we didn't pull enough, the effect of the train would be lost."

Inside the dress were two hidden gems: a blue bow at the waistband for her "something blue" and a little gold horseshoe as a good luck charm.

Princess Diana also wore a custom tulle veil that was hand-stitched with 10,000 micro-pearls to create what Elizabeth later called a "fairy dust effect" to Vogue U.K. "We used the same sequins on the gown itself so that it would also sparkle as Diana walked down the aisle," the designer said.

Princess Diana finished her bridal look with her family's Spencer Tiara, previously worn by her sisters, Lady Sarah McCorquodale and Lady Jane Fellowes, and her former sister-in-law, Victoria Lockwood.

Related: Princess Diana's Wedding Dress Secrets: Fake Clues, Hiccups and Hidden Touches by the Designers

The backup dress was not the only precaution the Emanuels took for the wedding day. In addition, they created an extra skirt should something spill on the dress. (It wasn't used even though makeup artist Barbara Daly revealed that Diana accidentally spilled some perfume on her dress. According to Daly, she told her to simply hold that spot on her dress as she was walking to make it seem like she was lifting the front of her dress so she didn't step on it. The royal was even spotted trying to cover the spot where the perfume spilled with her hand as she approached the altar.)

There was also a parasol made to match Princess Diana's dress just in case the London weather didn't cooperate.

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