A red jumper decorated with a flock of sheep that is one of the most enduringly recognisable of all the old clothes of Diana, Princess of Wales has sold for $1.1m (£885,000) in New York, making it the most valuable sweater ever sold at auction and setting a record for any article of her clothing, according to Sotheby’s. The auction house had estimated that the jumper would sell for between $50,000 and $80,000. Given the attention that Diana’s style has enjoyed in recent years, it might have been expected to smash that estimate, but perhaps not by 14 times. It may even have helped that the garment showed signs of wear, with some damage at the cuff. The jumper is the work of the knitwear brand Warm & Wonderful, which was founded by Sally Muir and Joanna Osborne in 1979. It was one of the pair’s first designs. “We were keen to make wool jumpers, so sheep were an obvious choice,” Osborne said. The pair did not know that Diana – then still Lady Diana Spencer, as it was a few weeks before her wedding – was going to wear the jumper, but Osborne described it as a “golden moment” when she did. About a month after the 19-year-old wore it, Osborne received a letter from Buckingham Palace saying the jumper had been damaged. “We were rather appalled so we immediately replaced it,” she said. They thought that the original, damaged jumper had been “lost in the mists of time” until, in March this year, Osborne found it when she was clearing out her loft. She described the moment: “It was kind of ‘could this honestly be the one?’. Rather than be hysterical, I was sort of questioning, and then I saw the cuff and was like: ‘Yes, that’s the one!’” Osborne thinks its graphic print has helped it to stand the test of time. “It’s very photogenic and it really does stand out … Plus it’s got a charm to it, and I think people need charm at the moment.” Its impact was consolidated in 2020 when the preppy New York-based clothing brand Rowing Blazers reissued it. It continues to sell the print in various iterations, from the “Diana edition” jumper (£270) to belts and bucket hats. There has been speculation about what Diana was communicating when she wore the design – a flock of white with a single black sheep. “I think she had a good sense of humour and she just thought it was funny and charming,” Osborne said. A recent Vogue article said: “In an era where Diana was often called Shy Di in the press,” it showed that “a rebellion was simmering underneath”. She wore the replacement version in 1983, and did so “with a lot more style”, said Osborne, appearing more confident in white trousers and shades. “Perhaps she was proud to have a black sheep, proud to stand out from the crowd; it’s all speculation though.” Earlier this year a velvet Victor Edelstein dress from Diana’s wardrobe sold for $604,800, five times more than its estimate. “It’s just unbelievable really,” Osborne said of the feeling that her decades-old design had done so well. “Thank you, Diana. We’re very grateful to her, to put it mildly.”