Princess Diana was allegedly preparing her youngest son, Prince Harry, to be the king over her “shy” eldest son, Prince William.

“I think William has been a bit of a surprise. He was a shy young man,” royal expert Richard Kay recalled on the “Palace Confidential” podcast Tuesday.

“Certainly, when his mother was still alive, she would tell me that she never really thought that William wanted the ‘top job,’ as she called it,” Kay added.

A royal expert claimed Princess Diana (seen above with her sons and King Charles III in 1994) was “preparing” Prince Harry to be king over his older brother, Prince William. Getty Images

“I think William (seen above with his mom and brother) has been a bit of a surprise. He was a shy young man,” Richard Kay recalled on the “Palace Confidential” podcast Tuesday. WireImage

Kay claimed his friend Diana, who died in a car crash in Paris in August 1997, “was preparing” for the possibility that Harry would be the one who succeeded his father, King Charles III.

“[Diana] had a nickname for Harry: She used to call him ‘Good King Harry’ — a throwback to medieval days,” Kay explained.

The “Spare” author, 41, and his wife, Meghan Markle, ended up quitting the royal family in 2020. William is slated to become the next king after Charles, followed by his son Prince George.

Kay (seen above with the late royal in 1996) claimed Diana told him she believed William didn’t want the “top job” as king. David O’Neil/Mail On Sunday/Shutterstock

Kay claimed Diana believed Harry would be the one “who succeeded his father,” King Charles III (seen above with Diana and their sons). Getty Images

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“Things haven’t worked out like that, and I think we are all rather grateful that they haven’t,” Kay said. “The consensus was ‘we got the right one.’ And, I think we got the right one in William as Prince of Wales.”

Kay noted how the dad of three, 43, has “grown into” his role as future king alongside his wife, Kate Middleton.

“What I quite like about him is that he is coming up with some quite different ways to approach royalty,” Kay revealed.

Kay said William (seen above with Harry) has “grown into” his role as future king. Getty Images

The Invictus Games founder (seen above with Kate Middleton, William and Meghan Markle) has had an estranged relationship with his brother and their father since leaving the royal family in 2020. POOL/AFP via Getty Images

“[William] recognizes that some of the aspects of monarchy is sort of antediluvian — doesn’t resonate well with the modern public,” he added. “I think he is aware that he’s going to have to make some big changes to ensure its survival.”

Page Six reached out to both William and Harry’s reps for comment but did not immediately hear back.

The Invictus Games founder has had an estranged relationship with his brother, William, and their father, Charles, since leaving the royal family.

Harry and his wife (seen above on their wedding day) accused the royal family of racism. Getty Images

Harry (seen above with William) has been trying to make amends with the royal family. Getty Images

Things got worse between the relatives when Harry and Markle, 44, accused the royal family of racism and released a Netflix series about their issues.

Then, in January 2023, Harry dropped his bombshell memoir, “Spare,” in which he alleged William physically attacked him over the “Suits” alum.

Last September, Harry met with Charles in the UK and chatted for just shy of an hour.