• In "The Lady Di Look Book," author Eloise Moran examines Princess Diana's style evolution. 
  • Moran revisits the claim that Diana refused to wear heels when she and Prince Charles were together.
  • "Diana wore shoes no higher than two inches out of respect to her husband's ego," Moran wrote.

Princess Diana avoided wearing high heels during her marriage to Prince Charles to avoid bruising his ego, according to an upcoming book about the late duchess' style. 

Eloise Moran, author of "The Lady Di Look Book," which is set to be released on June 21, revisited a claim about the Princess of Wales' meticulous choice of footwear previously reported by the Daily Mail's Richard Kay in his 1998 biography, "Diana: The Untold Story."

Moran, whose book was inspired by her Lady Di Revenge Looks Instagram account, which has over 118,000 followers, dives into the claim in the second chapter while discussing an outfit Diana wore to pick up Charles from Cirencester Hospital after he broke his arm in 1990.

"Diana styled an unbuttoned chambray shirt over a casual white T-shirt and wore it with a floral knee-length skirt and coordinating, but not quite matching, flat shoes," Moran, who described the ensemble as a "predivorce revenge look," wrote.

"For years, Diana wore shoes no higher than two inches out of respect to her husband's ego," she wrote. "Since he was the same height she was." The former couple stood equally at 5 feet 10 inches tall, according to the Daily Express. 

Princess Diana collecting Prince Charles from hospital in 1990. Foto: Tim Graham Photo Library via Getty Images,

Later in the book, Moran returns to Diana's footwear evolution, citing comments from luxury fashion designer Jimmy Choo that were published in "Diana: The Untold Story."

"As the estranged royal's confidence grew, so did her heels," Moran wrote about Diana. "Jimmy Choo recalled that at the start of their seven-year friendship, Diana always ordered flats, then as her marriage started to crumble, the heels got higher. 'First she went up to 2in, then 3in, then 3½ in, then ¾ in. They just kept creeping up and up,' said Choo."

Choo, Moran wrote, was a close confidante of Diana's. And in turn, the duchess was a "great fan" of his elegant '90s designs, Moran added.

Jimmy Choo created footwear for Diana and they became friends. Foto: Tim Graham Photo Library via Getty Images

"He often joined her at Kensington Palace, where they'd rummage through samples and collaborate on her next pairs," she wrote.

According to Moran, Choo even had a pair of pumps ready to deliver to Diana when she was expected to return from her August 1997 trip to Paris, where she was killed in a fatal car crash.

"She tragically never got to receive them, and Jimmy kept them in his personal collection in remembrance of his friend and best client," Moran wrote of the shoes.

Clarence House did not immediately respond to Insider's request for comment. 

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