Princess Diana's Original Black Sheep Sweater Is Going Up for Auction: All About the Rare Sale

Warm & Wonderful designers Sally Muir and Joanna Osbourne exclusively unstitch the history of Princess Diana's adored knit

Princess Diana’s iconic sheep sweater will soon be available for sale after it was discovered in storage over 40 years later.

On Monday, Sotheby’s announced the unusual news that the late Princess of Wales’ red sweater with a much-discussed black sheep motif will go up for auction in August. Nineteen-year-old Lady Diana Spencer famously wore the jumper (British parlance for a pullover) with jeans to then-Prince Charles' polo match in June 1981, one month before their royal wedding.

The fashion statement put British knitwear brand Warm & Wonderful on the map, and designers Sally Muir and Joanna Osborne received a letter from Buckingham Palace a few weeks later. A secretary said Diana had damaged her whimsical jumper and asked if it could be repaired or replaced. A new sweater was sent and the original became forgotten — until Osborne stumbled upon it this winter.

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“I was in the attic in February searching for a pattern, and I just happen to notice this old wine box in a corner — and there was a red sheep jumper wrapped in a cotton bedspread. It was well preserved, and I had a kind of Groundhog Day moment and thought, 'Could this be the one?' I looked at the cuff which had obviously been sewn back on, and I called Sal and said, 'I think I’ve found the actual real Diana jumper!’ ” Osborne exclusively tells PEOPLE.

“We had just sort of forgotten about it,” Muir echoes.

“We looked at all photographs of her wearing it, and we compared the two and we both felt certain that it was the actual one. We just knew because every jumper is different, so it was easy to see. So we called Sotheby's!” Osborne says.

The knit is now set to headline Sotheby’s inaugural Fashion Icons sale during New York Fashion Week. The sweater is offered with an estimate of $50,000 to $80,000, and the luxury broker notes the jumper has been “meticulously preserved.” Cynthia Houlton, Sotheby’s Global Head of Fashion and Accessories, exclusively tells PEOPLE that Diana’s favorite gym-going Virgin Atlantic sweatshirt, which RR Auction sold for $53,533 in 2019, is the closest comparison — but the sky’s the limit.

In January, Sotheby’s coordinated two other Princess Diana-related style sales. Kim Kardashian dropped $197,453 on a diamond and amethyst Garrard cross pendant which Diana wore in 1987. Two weeks later, Diana’s aubergine evening gown by Victor Edelstein sold for $604,800 — five times the pre-estimate — and made fashion history as her most expensive dress ever sold.

According to Houlton, what raises the stakes for the upcoming sweater sale is that the item has never come to market.

“They very randomly came across this sweater, it's not like they were sitting on this sweater for some period of time and then decided who they should sell it to,” she said of Muir and Osborne.

The expert explained that the original knit’s significance is further elevated by the fact that Princess Diana wore the design twice. While the original knit remained tucked away, the Princess of Wales slipped on her second version of the sweater for another one of Charles’ polo matches in 1983. She wore it with oversized sunglasses, a white blouse and white pants for the second spin — the meaningful rewear maybe hinting that she felt like an outsider.

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“Being at a polo match for Prince Charles in 1981, and then again in 1983, of course she was going to be photographed, of course that was going to be captured. I think that also really speaks to how much she really liked this specific pattern and this sweater,” Houlton tells PEOPLE, adding that “why she chose to wear this sweater in two very high-profile places” still sparks conversation today.

Speculating on the symbolism, Muir tells PEOPLE, “When she first appeared [in it], she was very much dressed by other people, and I think this was the start of her breaking free and choosing her own pieces,” she said of the repeat.

“The first time she was very much a young girl, and I think she thought it was amusing and fun, but the second time she wore it in a much more sassy way with a shirt underneath and a black tie and she looked much more in control,” Osbourne adds.

Though Muir and Osbourne never directly connected with Princess Diana and first learned that she wore their sheep sweater (which then retailed for $48) after seeing her photo in the newspaper, her support for Warm & Wonderful took the business to the next level. The Victoria and Albert Museum in London acquired one of the jumpers for its permanent collection in 1983, and Warm & Wonderful stopped producing the black sheep style in 1994.

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Online bidding for Princess Diana’s original red sweater opens Aug. 31 and will run to Sept. 14 through Sotheby’s. The jumper will also be displayed to the public at Sotheby’s Manhattan headquarters starting Sept. 7.

Fashion fans inspired to sport a lookalike of their own can preorder the Diana Edition Sheep Sweater from Rowing Blazers ($248). Warm & Wonderful reissued the historic design to Jack Carlson and his label in 2020, bringing the timeless style to the next generation.

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