Sarah Ferguson is paying tribute to Princess Diana on her birthday.

Ferguson took to Instagram to honor the late princess on what would have been her 63rd birthday. The former royal posted a photo of the two of them standing next to each other and smiling on the balcony at Buckingham Palace during the Battle of Britain Anniversary Parade in September 1990.

"Happy birthday to my dear friend, Diana. You were a pillar of light and love. And what a legacy you have left behind," she wrote in the caption. "I will forever remember our laughter and the kindred, kind spirit I found in you. I am sure you are watching over us always. Rest in peace my friend."

The two were very close during their time as members of the royal family, when Diana was married to Prince Charles and Fergie to Prince Andrew. Their friendship goes back much further than that, however, as the two first met when Diana was 14 and Ferguson was 15.

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Princess Diana and Sarah Ferguson on the balcony at Buckingham Palace.

Sarah Ferguson wished the late Princess Diana a happy birthday in an Instagram post. (Julian Parker/UK Press via Getty Images)

"Her mother and my mother were at school together, and they were best friends," Ferguson said on her podcast "Tea Talk with the Duchess and Sarah," in June 2023. "And Diana was my fourth cousin. You know, it's just extraordinary that we were brought together."

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The two joined the royal family just a few years apart from one another. Princess Diana married the now King Charles in July 1981, and Ferguson married Prince Andrew just five years later, in July 1986.

After her marriage to Prince Andrew, Ferguson became the Duchess of York, admitting on her podcast she often looked to Diana when learning the ropes.

"I remember when I first became a princess with Duch [Diana’s nickname], and I watched her work a room, and I just copied her. I mirrored her, how she did it, because she was just incredible," she explained. "She just immediately went in with her heart. Full heart, full energy, and she left everything outside the door."

Princess Diana and Sarah Ferguson at Trooping the Colour in 1991.

Ferguson and Diana both eventually got divorced from their royal husbands. (Jayne Fincher/Princess Diana Archive/Getty Images)

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Both women would eventually go on to divorce their royal husbands in 1996, with Diana and Charles finalizing their divorce that August and Ferguson and Andrew finalizing theirs in May.

Just one year later, Princess Diana tragically died in a car accident in Paris when she was 36 years old. An estimated 2.5 billion people then watched a young Prince William and Prince Harry walk behind their mother's casket during her funeral, as it was broadcast live on television globally.

"There’s nothing like it in the world," William said of his mother's passing in the HBO documentary, "Diana, Our Mother: Her Life and Legacy" in 2017. "There really isn’t. It’s like an earthquake has just run through the house and through your life and everything. Your mind is completely split. And it took me a while for it to actually sink in." 

In March 2024, William spoke at the Diana Award ceremony at the Science Museum in London. The program's main goal is to uplift those who work towards creating humanitarian and social change, according to their website

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A young Prince William sitting on Princess Diana's lap at the polo.

Prince William remembered his mother during his speech at the Diana Award ceremony in March 2024. (Tim Graham Photo Library via Getty Images)

When speaking at the ceremony, Prince William touched on the legacy his mother has left behind to the public and him personally. 

"She taught me that everyone has the potential to give something back; that everyone in need deserves a supporting hand in life," he said. "That legacy is something that both Catherine and I have sought to focus on through our work, as have the 50,000 young people who have received a Diana Award over the past 25 years."

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