Author Sean Smith made the surprising claim in his new biography about the 60-year-old duchess, “Sophie: Saving the Royal Family,” which was published July 17.

“She had an obvious and reasonable excuse: a friend at the palace explained, ‘Sophie decided it would be too upsetting for the crowd if she went,’” Smith wrote.

“‘She’s well aware that she looks like Princess Diana from a distance and made her decision in a caring and thoughtful way,’” he added. “‘The royal family fully supported.’”

Besides sharing Diana’s signature cropped blonde hair, Sophie also has blue eyes that resemble those of the late princess.

The pair looked so much alike that Sophie once commented on the striking similarities between her and Diana.

“I don’t deny that we do look alike,” she said in the 1990s, per Daily Express. “But I couldn’t ever compete with Diana’s image.”

“I’m not Diana,” Sophie added at the time.

Princess Diana tragically died on Aug. 31, 1997, after a car accident in Paris. She was 37.

The beloved royal was later honored in a Westminster Abbey service attended by more than 2,000 people on Sept. 6, 1997.

While one million people were estimated to have lined the route of Diana’s funeral procession through London, another 2 billion people were estimated to have watched on TV.

At the time, Sophie – then known only by her maiden name, Sophie Rhys-Jones – was dating Queen Elizabeth’s youngest son, Prince Edward.

The pair announced their engagement two years after Diana’s death, and married at St. George’s Chapel at Windsor Castle on June 19, 1999.

After embracing her new role as a full-time working royal, Sophie and Edward welcomed two children: Lady Louise Windsor, now 21, and James, the Earl of Wessex, now 17.

But Sophie’s time as a royal has not been without controversy.

In March 2023, Prince Edward and Sophie’s royal titles changed from the Earl and Countess of Wessex to the Duke and Duchess of Edinburgh following King Charles’ ascension to the throne.

Sophie’s new title put her at a higher rank than Prince Harry and Meghan Markle, the Duke and Duchess of Sussex, and Sophie was said to be “relieved” about the royal change.

“She no longer has to curtsy to someone in the family who has not only left royal duties but has spent the past three years criticizing the institution that Sophie works so hard to support,” a royal source claimed at the time.

Then, in May 2023, an 81-year-old great-grandmother was killed after she was struck by a police motorcycle escorting Sophie through West London.

One month later, Sophie faced backlash from royal fans after she allegedly scolded Prince William and Princess Kate’s daughter, Princess Charlotte, during the Trooping the Colour ceremony.