Kate Middleton has become the flagbearer of the Royal Family over the past few years.
The Princes of Wales has become one of the key representatives of the family, with a tougher role after the death of Queen Elizabeth II.
Royal expert and author Valentine Low notes: "Interestingly, behind the scenes, she’s a lot more steely, a lot tougher than we give her credit.
"She’s this nice-looking woman, dresses nicely, smiles nicely, adopts sort of fairly uncontroversial charities. You know, they think she’s slightly bland."
Earlier, the author also revealed the family was torn on how to deal with Meghan Markle, Prince Harry and Megxit.
Low said: "There were some people in other [royal] households, who felt it would antagonize Harry and Meghan and would go down badly and just keep the whole unpleasantness going. But it was Kate who really strongly made the argument."
He then revealed Kate "thinks very carefully about the long-term security and strength and stability of the royal family as an institution" because she is aware that "she’s one day going to be Queen."
The author added: "She’s good. She has a good eye on the big picture, the long game.”