Catherine, Princess of Wales is reportedly set to will rely on her "strong" relationship with sister Pippa and her family as she goes through preventative cancer treatment

Royal commentator Richard Fitzwilliams, 74, has now said Catherine's bond with her family is "absolutely pivotal" as she fights back to full health.

He told The Sun Online: "We know that she's got a very close and supported family, and secondly, that the support is under the radar.

"The Middletons are clearly a very, very important part of her and William's life. At the moment absolutely pivotal I would say.

"We know that there is a tremendously strong bond between her mother in her parents, also siblings, and also that they live in close proximity or relatively close proximity.

"So yes, absolutely, I think that this is important.

"I think the Middletons will be her rock, and they will be also tremendously helpful, and especially regarding the children."

Catherine and Pippa, 40, have shared a close bond that saw them share a flat in Chelsea, London, in their 20s and attending events such as Wimbledon together.

Pippa has now stepped out of the spotlight and lives with her former racing driver husband James Matthews, 48, and their three children Arthur, five, Grace, three, and 21-month-old Rose.

Her and Catherine's 69-year-old mum Carole Middleton also has son James Middleton, 36, with her 64-year-old husband Michael Middleton, with whom she ran the family's party supplies firm until 2023, when it was sold after it collapsed into administration.

Carole has revealed Catherine and Pippa were so close that when they weren't at school they "did a lot of modelling" for her Party Pieces company's merchandising material.