Ellen was saving up for a new home but, on a whim, spent £120,000 on five of Diana's dresses instead. Weeks later the Princess tragically died - and she began her incredible mission...

A hot evening in a packed auction room at Christie’s in New York in June 1997, and the atmosphere had reached fever pitch as some of Princess Diana’s most iconic dresses went under the hammer.

As the black velvet Victor Edelstein gown Diana wore to the White House in 1985 — famous as the occasion she danced with John Travolta — was bought for six figures, and gowns like the pearl-encrusted Catherine Walker ‘Elvis’ dress were snapped up, it was clear that this was a charity auction like no other.

Among the bidders was Ellen Petho, a mother and grandmother, who had snagged a coveted ticket. Mesmerised, she sat on the edge of her seat as a scarlet metallic jacquard chiffon gown, designed by Bruce Oldfield and worn by the Princess of Wales several times, reached the auction block.

‘Somebody in the entertainment industry was also interested in the dress and Ellen was determined not to be outbid,’ Ellen’s husband Louis tells me today. ‘There was a battle, but Ellen was fearless and kept going till the dress was hers.’

At the auction’s end, the self-made businesswoman — who, ironically, often shopped for herself at discount clothing stores — was the proud owner of five of Diana’s outfits. In total, they’d cost her $150,000 (£120,000) — money which the astute Ellen had saved to spend on a property.

On Friday, three of the dresses she bought (two were sold a few years ago) will again be available to buy at auction — this time at Julien’s Auctions in Beverly Hills, California, after Ellen died in January, aged 82.

ESTIMATED AUCTION PRICE $200,000 to $400,000: Princess Diana in the iconic Bruce Oldfield gown and (right) Ellen Petho with the dress

The memory of the evening she bought them is still fresh in her husband’s memory. Incredibly, Ellen had not told Louis that she was bidding for the gowns.

‘It was late at night when she called me and said, “Hey, let me tell you what I just did”,’ laughs Louis, of his wife’s purchases.

‘I was surprised, but Ellen always had good reasons for doing the things she did, so I trusted she knew what she was doing.

‘She didn’t want to go on with the advertising business she founded, and she knew about Diana’s passion for helping children. She bought the dresses to continue that legacy — and, of course, it turned out to be a wonderful thing.’

It certainly did. For rather than just wheeling them out to show off at swanky dinner parties, Ellen and her husband spent the next ten years travelling the length and breadth of the U.S. with the royal gowns, collecting more than a million pounds for causes close to Diana’s heart, including special needs and Aids charities.

In the process, the couple had experiences they could only have dreamed of, including becoming good friends with David Emanuel, who co-designed Diana’s wedding dress, and meeting two of Diana’s favourite couturiers, Bruce Oldfield and Catherine Walker.

Perhaps their biggest adventure of all was being invited to afternoon tea with Diana’s brother, Earl Spencer, at Althorp in 2007. ‘Never,’ says Louis, ‘did we imagine meeting Diana’s brother. But we did, and he was very nice.’

Such was her devoted reverence of the dresses, Ellen never touched them without gloves, even building a special temperature-controlled vault at her home in which to store them.

On sale this week will be a Catherine Walker bi-colour gown worn by Princess Diana for a gala dinner in 1991 in Toronto, Canada, which has a sales estimate of $100,000 to $200,000 (£79,000-£159,000), while another Catherine Walker dress, an ivory and black number worn to a private function, has a sales estimate of $60,000 to $80,000 (£48,000-£63,000).

ESTIMATED AUCTION PRICE: $100,000 to $200,000: Diana in the Catherine Walker gown arriving at the Royal York Hotel in Toronto

Not forgetting that Bruce Oldfield scarlet gown which so captivated Ellen all those years ago and which the Princess wore on several occasions, including to the London premiere of the film Hot Shots in 1991, and which has a sales estimate of $200,000 to $400,000 (£159,000-£318,000).

Martin Nolan, executive director of Julien’s Auctions, says these are ‘conservative estimates’ and they may go for more. ‘Many people can remember seeing Diana in some of these dresses,’ he says. ‘They’re beautiful creations and works of art, but more than anything they’re a connection to Diana, whose life was cut short and who is still missed.’

More than anything, Ellen’s family hopes the purchaser will see the dresses as Ellen did: as vehicles for good deeds.

Certainly, one can’t help but contrast Ellen’s philanthropic use of the dresses to the fate of another iconic gown: that of Marilyn Monroe’s ‘Happy Birthday Mr President’ performance — the most expensive dress ever sold at auction after it went for $4.81 million — and which was, controversially, worn by Kim Kardashian to the Met Gala in 2022.

Martin Nolan, who also oversaw the auction of that Monroe dress in 2016, says: ‘When Ellen bought these dresses, she had no idea that Diana would be gone so soon — but she resolved after her death that they were going to mean something, and she made that happen.’

Ellen’s remarkable involvement with Diana’s dresses came about by accident. She and Louis, who met as teenage sweethearts and were married for 60 years, raised their three daughters, Karrie, Christine and Katherine, in Michigan.

Ellen, a stay-at-home mother, went back to college as a mature student in 1988, earning a degree in advertising and design before setting up her own interior design business and an advertising company.

Ellen and her daughters were fans of the princess, but it was her youngest daughter, Katherine, then 12, who was most captivated when Charles and Diana announced their engagement.

Over the years, mother and daughter collected royal memorabilia as they followed the twists and turns of Diana’s life. When the sale of 79 of Diana’s dresses was announced some 26 years ago, Ellen purchased a $250 catalogue from Christie’s as a gift for Katherine to ‘round off her collection’ and was delighted to find two tickets for the preview of the auction inside the book.

ESTIMATED AUCTION PRICE $60,000 to $80,000: Catherine Walker dress worn to a private function

But Katherine, then a 28-year-old teacher, could not get time off work so Ellen took a friend to the preview. Ellen was thrilled to discover she was one of only 600 permitted to attend the auction — and began to form a plan to use $150,000 she’d saved for as many of Diana’s dresses as possible, instead of the property investment she initially intended.

‘When our mother received the catalogue, she’d read the inscription inside about Prince William telling his mother that the dresses shouldn’t sit in her closet; that they should be out in the world and doing good things for different communities,’ says Ellen’s eldest daughter Karrie, now aged 60. ‘I think that’s what inspired her.’

Karrie and her two sisters speak to me by telephone from Karrie’s kitchen, near the town where they grew up. Were they surprised when their mother told them what she had done? ‘Yes!’ they exclaim. ‘Our mother was an adventurer,’ Christine adds fondly.

Two months after the sale, the terrible news of Diana’s death in a car crash stunned the world, including the Petho family. ‘She was dumbstruck when Diana died; devastated — like everyone,’ says Karrie. ‘I think it made it even more important that she do this work and raise money for causes Diana supported.’

Ellen had mannequins made for the five dresses, as well as custom-designed linen carrying bags, each embroidered with a red rose, one of Diana’s favourite flowers.

Surely she must have been tempted to try them on? ‘She never tried them on — it would have destroyed the magic,’ says Louis. ‘She treated them with reverence.’

Ellen’s daughters never asked to try them on. ‘Our mother felt she was the guardian of these dresses, and we respected that,’ agrees Karrie. Instead, Ellen displayed the dresses at charity events across the U.S. ‘I often saw people come to the exhibits and they’d start crying. It was the emotion of losing Diana and the memories,’ her husband says.

Ellen answered many calls from charities. ‘She once got a call from a lady in Florida who had a mobile dental surgery on a converted bus that would go into poor neighbourhoods and treat kids whose parents didn’t have money for dental appointments,’ says Louis.

‘She asked if Ellen could help raise money to keep the service going, and Ellen found a venue, shipped the dresses, went off to Florida and raised $30,000 over a couple of days, all because people loved to see those dresses,’ says Louis. ‘She also raised a lot of money for camps that hosted children with Aids, because she knew that had been a cause close to Diana’s heart.’

Ellen and her husband made multiple trips to London, meeting some of the designers who made clothes for Diana. ‘David Emanuel became a close friend of ours and Bruce Oldfield was extremely gracious when he found out that Ellen owned the red dress,’ recalls Louis, 83.

‘We went to Catherine Walker’s studio. She was ill at the time [French-born designer Catherine Walker, who worked with Diana for 16 years, died of cancer in 2010] and we were having a very nice conversation with her husband when she walked in.

‘She told us one of the dresses, an ivory and white one, was made for a private function, probably dinner in someone’s house, and that’s why there are no official photographs of Diana wearing it.’

Diana’s brother Charles Spencer invited the couple to his home. ‘We had a tour of the house and gardens, then we were taken to Earl Spencer’s study where he was waiting and had tea laid on,’ says Louis.

Ellen continued her charitable work till her health deteriorated due to congestive heart failure. The family plans to use some of the money from the sale of the dresses to establish an art and design scholarship for mature students.

Interest in the items is intense because Diana’s dresses come on the market so rarely, according to auctioneer Martin Nolan, who has managed sales of many notable collections, including the property of Muhammad Ali, Michael Jackson and Elvis Presley, among others. Mr Nolan says: ‘Here in California, there’s someone who lives not far from the auction house who is very interested. It’s going to be an exciting sale.’