Prince William at the 2023 United for Wildlife summit
Prince William, seen here at the United for Wildlife summit in Singapore on Nov. 6, 2023, was left furious at the"Harry & Meghan" series. Photo: Wilmok Official/Instagram Wilmok Official/Instagram

A new book about the royals revealed how Prince William was said to have reacted over Prince Harry's interview in the Netflix documentary "Harry & Meghan". He was said to have been furious at a statement that he felt was targeted at his wife, Kate Middleton.

In the docuseries, which aired in December 2022, the Duke of Sussex insinuated that for the men in the royal family, "there can be a temptation or an urge to marry someone who would fit the mould - as opposed to somebody who you perhaps are destined to be with".

He added: "The difference between making decisions with your head, or your heart."

He was reportedly taking a jab at his older brother, suggesting that he did not marry Kate Middleton for love. This inference left friends of the royal family greatly surprised, according to royal author Robert Hardman.

"The clear inference that he was talking about his elder brother astonished friends of the family," he wrote in his new book "Charles III: New King. New Court. The Inside Story" serialised by the Daily Mail.

Hardman quoted an unnamed friend who said: "On top of all the other breaches of trust, here was Harry making a blatant attack on Catherine. For William, this was the lowest of the low."

On the other hand, the biographer added that "opinions were divided" over whether his comments were a slight against the Princess of Wales. There were reportedly also thoughts that they could have been a case of "Harry shooting his mouth off" with another round of baseless assumptions and allegations.

Aside from the Netflix docuseries, Prince William was also left "mortified by the casual betrayal of so many fraternal secrets" in his brother's memoir, "Spare". Hardman writes that neither the Prince of Wales and Kate Middleton have read the tome. They have instead received briefings from aides on key points.

"Whatever the rights and wrongs, I hope that people feel I behaved properly in keeping my counsel," the Prince of Wales has said according to one of his royal aides.

"Charles III: New King. New Court. The Inside Story" is out on Jan. 18. Kate Middleton will be out of the public eye or a couple of months or more after she underwent an abdominal surgery on Tuesday at The London Clinic. She is expected to resume her royal duties after Easter. Prince William will be by her side as she recovers in the hospital for 14 days and during the early days of her recuperation at their home in Windsor.