Mr Quinn told Express.co.uk: “Princess Anne has never really struggled, she’s famously quite supportive of Charles.
“And she is kind of a tougher character than Charles, because I think she has always known she wouldn’t become the monarch, whereas Charles [growing up] was under that pressure.
“And I think something similar will happen in the younger generation too.”
The author said there is “definitely a parallel” between Anne and Charlotte, who like her great-aunt already appears to have a strong personality despite being only a few weeks away from her eighth birthday.
She also explained how Prince William’s approach to raising a future King, and said: “Just as William learned from an early age what his future entailed, taking lessons in kingship from his grandmother when he was a schoolboy at Eton, he is keen that George – who has a quieter personality than his more extrovert sister – knows what will one day be expected of him.”
Speaking of the weight on George’s shoulder, Mr Quinn said: “George will feel although he has a role, and he’s very important and he will already be aware that he’s very important.
“On the negative side, it represents a kind of pressure. And so I think he’s looking to his sister who is more grounded.”
Charlotte, Mr Quinn concluded, will be a “really good” support for her elder brother if she doesn’t envy his position or being less in the spotlight than him.
He said: “With the pressure of being number one, you need someone who’s not really jealous that you’re number one.
“And I think that was the problem with Harry and William, you need someone who just accepts that situation and supports you. So I think Charlotte will be really good for George.”
Charlotte appear to be already supporting her elder brother as Kate and William have chosen to have the two children mark many firsts in their lives together.
Brother and sister carried out their first ever Christmas Day walkabout in Sandringham in 2019, despite George being two years older than Charlotte.
Similarly, they attended together key events marking the Platinum Jubilee in June 2022, including their first official visit to Cardiff.
In September, Charlotte and George once again supported each other as they attended together the funeral of their great-grandmother Elizabeth II.
Gilded Youth by Tom Quinn, published by Biteback, is available in hardback at £15.