Princess Diana—born Lady Diana Spencer—was actually from stock even more aristocratic than the British royal family.Diana was “exceptionally proud of her heritage” and of being a Spencer, a new book claims.In fact, when life as a royal and with husband Prince Charles would get especially tough, she would turn to a surprising mantra that tied back to her roots.

Legend goes that the Spencer family—the birth family of the late Princess Diana—is actually more blue blooded than the royal family Lady Diana Spencer married into when she married Prince Charles on July 29, 1981. It was a fact Diana was proud of, and became the basis of a mantra Diana repeated to herself when life with Charles (and inside the confines of the royal bubble) got to be too much.

In his new book Dianaworld: An Obsession, Edward White wrote that Diana was “exceptionally proud of her heritage” and of being a Spencer (per Marie Claire). In the book—which hit shelves April 29—White added that Diana appreciated “centuries of inherited specialness which supposedly was the very thing that allowed her to relate to everyone.”

Princess Diana on November 9, 1989.

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Princess Diana wearing the Spencer family tiara in April 1983.

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Ever proud of her Spencer heritage, Diana eschewed the offer to wear a tiara from Queen Elizabeth’s extensive collection and chose to wear the Spencer tiara on her wedding day instead. She also chose to send her sons Prince William and Prince Harry to Eton College—where Diana’s father and brother attended—rather than to Gordonstoun, where Charles and his own father Prince Philip had gone. In short, Diana “was far prouder” of being a Spencer “than of being royal,” according to White.

When life—and her marriage to Charles—got rocky, Diana’s friend Rosa Monckton told White that “Whenever things got too much for her, she would say to herself, ‘Diana, remember you’re a Spencer.’”

Princess Diana (wearing the Spencer tiara) and Prince Charles on their July 29, 1981 wedding day.

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Another of Diana’s friends, Elsa Bowker, also said “that the princess took great strength from her Spencer heritage.”

Charles and Diana eventually separated in 1992 and finalized their divorce in 1996, just one year before Diana’s far too soon death in a Paris car accident on August 31, 1997. When Diana would argue with Charles about their impending divorce, Diana reportedly told the future king, “When I came here, I had my title. I don’t need your title.”

Princess Diana on July 1, 1983.

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That said, Diana—though from aristocracy—prided herself on being “as she put it once, ‘Closer to people at the bottom than to people at the top.’” (The People’s Princess, indeed.)

White added that even up to the present day, “the Spencers are as close to being the people’s aristocrats as it’s possible to get—and Diana remains at the center of it all.”