After two failed cover attempts, the former Princess of Wales agreed to move forward “without seeking permission from the palace” this time

Princess Diana visits the Royal National Orthopaedic Hospital in London on July 1, 1992 and Linda Evangelista modeling French designer Michel Klein’s women’s 1992 spring-summer ready-to-wear line in Paris. Photo: Jayne Fincher/Princess Diana Archive/Getty Images;  julio donoso/Sygma via Getty Images

There’s a story behind every magazine cover — and the December 1991 issue of British Vogue featuring Princess Diana is no exception.

How the cover came to be, as well as the late Princess of Wales’ friendship with then-British Vogue editor-in-chief Liz Tilberis, is covered in a recent episode of the podcast Blow Up: When Liz Tilberis Transformed Bazaar, a six-part series that examines the woman who went on to helm Harper’s Bazaar before her death in 1999 from ovarian cancer.

Princess Diana on the cover of the December 1991 issue of “British Vogue,” as shot by photographer Patrick Demarchelier.Patrick Demarchelier/Vogue Magazine

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Long before that, though, was Diana’s 1991 British Vogue cover, which Tilberis orchestrated. The cover happened after two previous failed attempts, both of which were shot down by the palace, according to the podcast. But, when it came to the cover that finally took — shot by photographer Patrick Demarchelier and featuring a closeup of Diana with a short haircut, long nails and wearing a black turtleneck — none other than supermodel Linda Evangelista might have been the one to push it over the line and actually make Tilberis’ long-held dream happen.

In the fall of 1991 at a reception for the British Fashion Council Awards, Princess Diana asked Tilberis to introduce her to Evangelista.

“Diana had always wanted to meet Linda,” said Patrick Jephson, Diana’s former private secretary. “She was intrigued by the supermodels, because those girls were the superstars of the time. And she was intrigued as to how they coped with the fame, you know?”

Left to right, Linda Evangelista, Christy Turlington, Gianni Versace, Claudia Schiffer and Carla Bruni in 1991. Gamma-Rapho via Getty

Diana, after all, did know a thing or two about being famous. When they met, “I think she asked us, Christy and Naomi, if we, if our diet was, like, McDonald’s and cigarettes,” Evangelista said. “At that point, it was whatever I wanted to eat, you know?”

Tilberis and Princess Diana’s hairstylist Sam McKnight hatched a plan for the four of them to have breakfast together at Joe’s Cafe, owned by a friend of Tilberis and attached to Joseph’s of London. “It was very trendy in Chelsea, where all the cool stores are,” McKnight said.

They wanted somewhere “where we can talk, we can all chat and giggle,” McKnight added. “And we don’t want anyone to see us. It was going to be a private thing. So Liz arranged for them to open the cafe early. Now, the princess would have been absolutely mortified if she had thought they had opened up just for her. So they had to kind of pretend they were open.”

Princess Diana and Liz Tilberis attend the Council of Fashion Designers of America Gala Ball in New York City.Antony Jones/UK Press via Getty Images

To make it not look like they had closed down just for Princess Diana, Tilberis and McKnight cast attractive people to sit at the tables of the cafe and pretend to be patrons — though they were really the staff of Joseph’s.  They were asked to sit at the cafe’s tables, “and so it looked like it was fancy,” McKnight said. (Princess Diana didn’t know about this ruse, nor did Evangelista, the latter revealed in the episode.)

“I was nervous because I really loved her and I respected her,” Evangelista said of the former Princess of Wales. “And then you meet her. I just remember how lovely she was. And we had some giggles, and she was, like, very open and honest.”

McKnight added of the sit-down, “There was no sort of world-changing chat. It was chit chat, you know — it was kind of giggling and gossiping.”

The secret mission of the cafe meetup, McKnight said, was for Tilberis to convince Diana to let her use the closeup shot taken by Demarchelier for the December 1991 cover.

A photograph of Princess Diana shot by Patrick Demarchelier that was turned down for the December 1990 cover of ‘British Vogue’ by the palace.

Tilberis had tried two times before to get Diana to appear on the cover of British Vogue. The first, an informal shot photographed by Demarchelier, was a black-and-white image of Diana playing with her sons Prince William and Prince Harry in a barn at the family’s country home, Highgrove. The palace said no to the cover. Later, British Vogue wanted to put a more formal shot of Diana in a tiara on its cover. The palace, again, said no.

“There was no explanation, but Liz had a feeling it was a way of reining in the princess, whose restlessness was becoming publicly apparent,” Blow Up co-host Cynthia True said.

At last, in Joe’s Cafe, it was an urge from Evangelista that pushed Diana over the line. By the end of their breakfast date, Diana said yes to appearing on the cover, “and told Liz to move forward with the chosen photo without seeking permission from the palace,” True said. “She would handle it.”

“And Liz got a magnificent cover,” McKnight said on the show. “And she did not force, she waited for it to organically happen, you know?”

Princess Diana speaking in January 1995 at the CFDA party in New York City.Pool Photograph/Corbis/Corbis via Getty Images

The December 1991 edition of British Vogue went on to become a bestseller, and featured Princess Diana on the cover of the magazine for the first time in 10 years. The following month, Tilberis was named editor-in-chief at Harper’s Bazaar.

Her friendship with Princess Diana certainly didn’t end after Tilberis finally landed her coveted Princess of Wales cover, though. The two met because British Vogue editors advised the Princess of Wales on her official wardrobe, and by the time Tilberis became editor-in-chief of the magazine in 1987 after the departure of Anna Wintour for Vogue’s American iteration, she and Diana were friends who had lunch together frequently, bonding over both being mothers of young boys.

The two took part in what the podcast called  “marathon phone calls” after Tilberis moved to New York City to accept the job at Harper’s Bazaar in 1992. “Liz was, I would say, kind of like a big sister-ish figure, a big sister that accepted Diana as she was,” Jephson said.

After Tilberis’ ovarian cancer diagnosis in 1993, according to the episode, Princess Diana was one of the first to call when she was out of the hospital and stayed in touch with her almost every day, either by phone or via a handwritten note transmitted by fax.

“She called a lot and they would have a lot of chats,” said Tilberis’ former assistant Stephanie Albertson. “That was a very real friendship, and I remember once she called and the message was, ‘I’m just watching a movie with the kids.’ And what did she say? She said something like, ‘I’m sitting in bed eating popcorn with the kids — just have her call me back.’ ”

Princess Diana at Eton for Prince William’s first day there on Sept. 6, 1995. Tom Wargacki/WireImage

As Tilberis underwent chemotherapy, “Diana distracted her with light gossip about mutual acquaintances in London, and Liz ignored the frequent call waiting beeps,” according to True. “ ‘What’s that?’ the princess asked. When Liz explained, Diana sounded relieved. In England, she said it would be MI5. The Ministry of Intelligence was rumored at that time to have bugged the princess’ phone.”

According to Jephson, “A lot of what I saw in the friendship between Liz and Diana was an acceptance of there being no need to be anything other than yourself. And for Diana, that was refreshing and different and rare, because she didn’t have the kind of husband or partner that luckier people have in whose presence she could relax and be herself. So when she had a friend like Liz, who didn’t expect her to be anything more than she was, who didn’t want her to be anything other than happy and relaxed, this was, I think, a weight lifted from her shoulders.”

For Tilberis’ part, according to True, she said there were very few people, apart from Diana, who knew how to talk to someone with a cancer diagnosis.

Princess Diana and Liz Tilberis attending the 1996 Met Gala.Stephane Cardinale/Sygma via Getty Images

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When it came to photographing Diana for British Vogue, Tilberis felt that previous portraits of her for the magazine were too formal, failing to capture the warm, funny woman Tilberis knew so well. They shared a sense of humor, and at one of their many lunches, when Tilberis complimented Diana on her Chanel loafers, Diana answered dryly that the entwined Cs of the fashion house’s logo stood for Prince Charles and Camilla Parker Bowles, who were by now known to be romantically involved, something Princess Diana was perhaps more aware of than most anyone.

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When Tilberis won an award at the Council of Fashion Designers of America (CFDA), Princess Diana honored her friend in a speech in New York City in January 1995. Tilberis then accompanied Princess Diana at what would become her one and only Met Gala appearance, which took place in December 1996 with the newly divorced Diana wearing Dior. Though it was widely known that Tilberis was ill, absolutely no one would have expected that Diana would die before her dear friend, losing her life as a result of injuries sustained in a car accident on Aug. 31, 1997 at just 36 years old — two years before Tilberis herself died of cancer at 51 years old on April 21, 1999.