Exclusive: New Princess Kate photo released as Prince William shares rare personal birthday message….See More

Prince William has paid tribute “to the most incredible wife and mother” in a very personal birthday message.

A new picture of Princess Kate has been released to mark her 43rd birthday today, alongside a rare personal message from her husband, Prince William.

The previously unseen image was taken in Windsor last summer by photographer Matt Porteous.

William paid tribute “to the most incredible wife and mother” in the post, and added: “The strength you’ve shown over the last year has been remarkable. George, Charlotte, Louis and I are so proud of you. Happy Birthday, Catherine. We love you. W.”

Kate’s birthday is not usually marked by a message from the prince or the release of a new image. But it is understood that William wanted to mark the occasion following Kate’s “brutal” year receiving cancer treatment.

Earlier on Thursday, King Charles and Queen Camilla wished Kate a happy birthday on their social media channels by sharing a photo of the princess taken on Christmas Day.

The royal couple have adopted a new approach to social media over the past 12 months, choosing to share updates on their terms.

Kate shared her cancer diagnosis in a poignant video, and later revealed she had completed her course of chemotherapy in a short film featuring her family.

To mark Prince William’s birthday in June, the occassion was marked by a personal message from Kate, who wrote: “Happy birthday Papa, we all love you so much! Cx.”

Kate is expected to spend her 43rd birthday with her closest friends and family today.

Following her “dreadful” year receiving cancer treatment, Kate, Prince William and their three children will mark the occasion quietly at home.

She is set to spend the day with her closest friends, before enjoying an intimate evening meal with William, Prince George, 11, Princess Charlotte, nine, and Prince Louis, six, pictured.

Kate was admitted to hospital for “planned abdominal surgery” last year, just a week after her 42nd birthday. She spent two weeks at the London Clinic before returning home for further recovery.