Princess Diana's original black sheep jumper is going to auction after being found in an attic

The iconic black sheep jumper worn by Lady Diana Spencer soon before she married Prince Charles is going to auction.

The woollen jumper was recently discovered in an old wine box hidden inside an attic, 40 years after it was worn by Diana to a polo match in Windsor in June 1981.

Soon after the jumper was seen on Diana, it was returned to Sally Muir and Joanna Osborne, founders of the label Warm & Wonderful because of a tear at the cuff.

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An accompanying letter from Buckingham Palace requested that the garment be repaired or replaced. Instead, a new jumper was knitted for Diana.

Osborne believes Diana may have ripped the jumper on her sapphire and diamond engagement ring, presented to her from Prince Charles just months before.

When the new jumper was sent to Diana, Osborne thought the original had been lost.

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But in March, she discovered the jumper while searching her attic looking for an old pattern.

It was preserved underneath an old cotton bedspread.

She got in touch with Sotheby's which has since given the garment an auction estimate of £50,000-£70,000 (approx. 95,000 - $133,000 AUD).

It will be auctioned online between August 31 and September 14.

Speaking to The Telegraph UK Osborne said: "We didn't think we had any of the original sheep jumpers, because at the time, we were so desperate to complete orders that we never owned one ourselves, so I couldn't believe I'd found the original Diana sheep jumper.

"It took a while to sink in. And we're so lucky it's not fallen to pieces."

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The jumper will be the star piece of Sotheby's Fashion Icons sale in New York.

Two years after Diana wore the original jumper at the polo, she was seen in the replacement in 1983, styling it with white jeans, a large white collar and a thin black ribbon tie.

Sotheby's said of the now-iconic design: "The Black Sheep sweater is one of the most iconic pieces worn by Princess Diana to ever come to market.

"The cultural impact of this moment from the 1980s is exemplified by the head of Rowing Blazers, Jack Carlson, who in 2020, requested to partner with the original designers and license the sheep design to be reproduced for his own fashion line.

"The business partners reported an outstanding response from consumers, emphasizing the immortality of Diana's taste and her influence on popular culture."

Sheep jumpers are now available to buy in a range of colours and a recreation was made for actress Emma Corrin to wear as Princess Diana in season four of The Crown.