Prince William and Princess Kate's public message to King Charles on his 76th birthday - details

Prince William, Princess Kate and King Charles waving
Prince William, Princess Kate and King Charles watch the RAF flypast from the balcony of Buckingham Palace (Getty)

The Prince and Princess of Wales have sent their best wishes to King Charles in honour of his 76th birthday on Thursday.

In a touching gesture, the royal couple took to their social media pages to share a photo of the monarch during a recent engagement alongside a caption which read: "Wishing a very Happy Birthday to His Majesty The King!"

The photograph was taken last month during Charles and Camilla's visit to Samoa, with the monarch sporting a beige suit with sunglasses and a ceremonial garland to open The King's Garden, at the Robert Louis Stevenson Museum in Apia.

King Charles wearing sunglasses and lei in Samoa
William and Kate shared a photo of the King in Samoa (X / @kensingtonroyal)

The royal family's social media account also posted a portrait of Charles, wearing a blue suit, taken at Buckingham Palace to mark the occasion.

The King is set to mark his birthday by opening two hubs designed to save and circulate tonnes of surplus food.

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The opening of the distribution centres will also mark the first anniversary of the Coronation Food Project, an initiative to support charities feeding the nation with unwanted food. He is set to open the initiative's first two Coronation Food Hubs – one in person and one virtually.

It is hoped the hubs will help charities like FareShare and the Felix Project to support communities in need. The hub the King is visiting will host a "surplus food festival," with meals created from food which would otherwise have gone to waste.

Charles will tour the new facility, meeting beneficiaries and representatives of food banks, schools and community groups.

The birthday celebration comes shortly after Princess Kate joined King Charles and Prince William at the Remembrance events last weekend.

Front row (L-R) Britain's Catherine, Princess of Wales, Britain's Prince William, Prince of Wales, Britain's King Charles III and Britain's Princess Anne, Princess Royal attend "The Royal British Legion Festival of Remembrance" ceremony at Royal Albert Hall
Prince William and Kate joined the King at the Festival of Remembrance over the weekend (CHRIS J RATCLIFFE)

The appearance marked a positive step towards Kate's return to public duties following the completion of her chemotherapy treatment.

Last week, Prince William opened up in an interview with UK print media in South Africa about the past 12 months, and how it's been "the hardest year of his life" amid his wife and father's cancer diagnoses.

Charles and Camilla arrive in Samoa
The King and Queen recently returned home from a trip to Australia and Samoa (Getty)

"Trying to get through everything else and keep everything on track has been really difficult, he said. "But I'm so proud of my wife, I'm proud of my father, for handling the things that they have done" before saying that "from a personal family point of view" the past year has been "brutal".

Sharing an update on Kate, he added that she's "doing really well". The King and the Princess of Wales's health battles were confirmed within weeks another in February and March earlier this year.

Charles has resumed his treatment after returning to the UK from his tour of Australia and Samoa with wife Camilla, while Kate, 42, completed a course of preventative chemotherapy in September.