Kate Middletons carefully planned path to the throne revealed as expert says she played the long game

Kate Middleton's remarkable rise from middle-class university student to the Princess of Wales wasn't accidental — according to multiple royal experts, it was carefully planned from the very beginning.

Royal author Simon Vigar wrote in "The Four Wives of Windsor" that Prince William's "right-hand man" said Kate believed in "steady progress" as she learned the ropes of royal life, explaining, "We're not going to rush our fences."

"Catherine is no wallflower, somebody told me," Vigar told Fox News Digital. "She's got definite views about things. William obviously trusts her implicitly, and they need people like that. The queen needed Philip. Charles needs Camilla. And William needs Catherine. [And] she's very clever. I reckon she's probably the cleverest of a lot of them."

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Vigar said that as a newcomer to the royal family, the was determined to master the role, carefully carving out her place without overshadowing the monarch.

"For instance, they had various charitable interests, ranging from wounded service personnel to early years education and homelessness," Vigar explained. "The person who linked all of those together under the mental wellbeing banner was Catherine. It wasn't Harry or William. She was the one who said, 'Do you know what the common denominator with all of this is? It's mental wellbeing and mental health.'"

"And so, they started a new charity, sort of an umbrella over those," said Vigar. "She will have learned from the other consorts. You're always one step behind, but you're there as a support. If you think something's not quite right, you say it. Catherine's the person that William can trust absolutely implicitly to give him impartial advice."

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Kate's journey to becoming the Princess of Wales was unlike that of the royal women who came before her.

"Its a huge social leap that happened with Catherine," said Vigar. " was a member of the aristocracy. Camillas pretty posh, as we say in this country, not quite as posh as Diana, but posh."

"Catherine's middle class," he continued. "Her parents worked very hard. They built their own business. They were able to send their children to private school. ... And it got her to St. Andrews University, where she met William, of course."

married in 2011. Since then, Kate has devoted herself to several charitable causes and organizations focused on early childhood development, mental health, sports and the outdoors, among others.

"I think Kate was born for this role, as odd as that may sound," Christopher Andersen, author of "Kate!," told Fox News Digital. "She has a preternatural calm, a sense of self and confidence that borders on regal. I think she could have stepped into the role as queen-in-