Royal experts explain how Carole Middleton has become a "second mum" to Prince William

The Princess of Wales returned to royal duty this month, marking her first public appearance since her cancer diagnosis earlier this year.

The 42-year-old mother of three has reassured the public that she is "making good progress" and hopes to attend some public events this summer. However, she has stressed that she is "not out of the woods yet", and as the Princess of Wales continues her treatment, she is said to be leaning on her close support network of loved ones.

Two people who have played a major part in Princess Kate's recovery are her husband Prince William and her mother Carole Middleton, with the pair reported to have become extremely close amid Princess Kate's illness and recovery.

On closer inspection however, the future king and his mother-in-law were very close beforehand, with royal experts reporting that William adopted the Middletons as a second family when he started dating Kate.

According to commentators, Carole Middleton is very maternal with William, preparing his favourite treat - cheese on toast, and buying in his favourite sea salt chocolates when she sees him.

In fact, it has been noted on multiple occasions that Carole Middleton is like a "second mum" to the Prince of Wales. This is something that psychiatrist Max Pemberton reportedly opened up about in an article for the Daily Mail.

"We all know how tricky life with in-laws can be. And yet sometimes, they provide an alternative type of family to ours, which is welcome," Pemberton stated. "It's said William considers Carole a second mum. Of course, he lost his own at a tender age, so Carole may represent that maternal figure he's lacked."

"Carole and Michael are just as much family to William as they are to Catherine," Ingrid Seward, editor-in-chief of Majesty Magazine has also explained previously. "He loves Carole being around to help as she has been with the children from the beginning and it is easy and reassuring having her invaluable help."

It is not known when the Princess of Wales will return to her role on a permanent basis, but she has thanked the public for their "continued understanding" and those "who have so bravely shared their stories" with her.

We will continue to update this story.