Kate Middleton Treats Prince William as ‘Fourth Child,’ Book Claims

Princess Kate Middleton may be married to Prince William, but sometimes he’s just like one of the kids, according to a new book about the royals.

An excerpt from Tom Quinn’s upcoming book, Yes Ma’am: The Secret Life of Royal Servants, was published in The Times of London on Thursday, February 6 — and it contains some insightful apparent details about the couple.

The book, which will be published in the U.S. on February 25, features interviews with royal insiders and former staffers close to Kate, 43, William, 42, and other royals.

An unnamed source interviewed by Quinn said: “I don’t know where William would be without Kate — she hasn’t had everything done for her throughout her life, so she calms him down when he gets a bit fractious.”

“She said he sometimes has to be treated as her fourth child,” the source added.

Meanwhile, a former Kensington Palace maid told Quinn that Kate had to teach William about aspects of parenting that aren’t typical for royals.

“Kate had to explain many of the things that parents outside the royal family do with their children as a matter of course — she had to show him how to give the children a piggyback, for example. William said very quietly, ‘My father never gave me a piggyback,’” the former maid said.

Unsurprisingly, Kate also had to learn a few things about royal etiquette and protocol early on — including a funny incident involving her wardrobe. “Before Kate realised that as a senior royal you have to dress carefully, having taken advice, she once bought an outfit that William considered inappropriate,” one advisor is quoted as saying. “He told Kate she looked as if she’d just run through a charity shop covered in superglue. Everyone thought this was very funny, including, to her credit, Kate.”

In another portion of the excerpt, Quinn wrote that William and his father, King Charles III, “are prone to tantrums if things are not done to their liking.”

“They both get irritated very quickly,” a former staffer told Quinn. “They are very picky. It comes naturally to them.”

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Other parts of the book detail palace staff’s perspectives on working for Queen Camilla, Meghan Markle, and Prince Harry.

Kate and William have been married since 2011. They share three children together: Prince George, 11, Princess Charlotte, 9, and Prince Louis, 6.

The couple are typically private about their marriage but have become more open since announcing Kate was battling cancer in 2024. (She announced she was in remission in January 2025.)

“To the most incredible wife and mother. The strength you’ve shown over the last year has been remarkable,” William wrote in a social media post for Kate’s birthday on January 9. “George, Charlotte, Louis and I are so proud of you. Happy Birthday, Catherine. We love you. W.”

Kensington Palace did not immediately respond to Us Weekly’s request for comment.