The Prince and Princess of Wales have released a new photograph of Princess Charlotte in honour of her ninth birthday

In the photo, which was taken in Windsor recently, Charlotte had her hair down and smiled for the camera as she leant against some railings by a flowery hedge, wearing a blue denim skirt with a darker-hued top and a maroon cardigan.

The post was captioned: "Happy 9th Birthday, Princess Charlotte! [Birthday cake emoji] Thank you for all of the kind messages today. [Photo by] The Princess of Wales."

The post comes a week after another of Catherine's photographs was used to mark Prince Louis' sixth birthday on 23 April.

The couple captioned the post on their official Instagram page: "Happy 6th Birthday, Prince Louis!

Thank you for all the kind wishes today."

In March, Catherine apologised after the legitimacy of a Mother's Day photograph of her and her children, which also includes 10-year-old Prince George, was questioned because of digital alterations.

A statement released by the princess explained: "Like many amateur photographers, I do occasionally experiment with editing.

"I wanted to express my apologies for any confusion the family photograph we shared yesterday caused. I hope everyone celebrating had a very happy Mother's Day. C."

It was the first official picture of the royal since she underwent abdominal surgery in January and stepped away from the spotlight during her recovery.

Catherine later revealed she had been diagnosed with cancer as speculation grew about her stepping out of the spotlight and she is continuing to receive preventive treatment.

Her husband, Prince William, recently dec lared his family were "doing well" amid his wife's medical issues while on a visit to a male suicide prevention charity in Newcastle, North East England.

William was asked by 60-year-old Julie Cain outside the James' Place centre: "Do you mind if I ask how your wife and children are?"

He replied: "All doing well, thank you. Yes, we're doing well."