PRINCE William and Princess Kate have wished King Charles a happy 76th birthday with a "cheeky" Instagram snap.
The heartwarming message was posted on the joint social media account of the Prince and Princess of Wales.
It read: "Wishing a very Happy Birthday to His Majesty the King!"
The post was accompanied by a cheeky snap of Charles, who looked relaxed in sunglasses with a floral garland draped round his neck.
Meanwhile, the monarchy's official social media accounts posted a congratulatory message with a more formal portrait of the King standing in the White Drawing Room at Buckingham Palace.
The King celebrated his 76th birthday by marking the occasion with a visit to a surplus food festival.
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Charles is treating the day as a normal working one and carrying on with his duties despite facing a personally challenging year in which both he and the Princess of Wales were diagnosed with cancer.
The monarch will open the first two Coronation Food Hubs on the first anniversary of the launch of his Coronation Food Project, designed to bridge the gap between food need and food waste in the UK amid the cost-of-living crisis.
Charles headed to Deptford in south London to formally unveil the first hub, tour the centre with London Mayor Sadiq Khan, and attend the surplus food festival being staged to celebrate the royal visit, before virtually opening another hub in Merseyside.
He was greeted by Sir Kenneth Olisa, Lord-Lieutenant of Greater London, and taken to the entrance of the Deptford hub where the King was greeted by Mayor.
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Volunteers from the Felix Project, who will run the Deptford hub, were seen waving flags and cheering jubilantly as the King arrived.
Project chairwoman Dame Martina Milburn, Baroness Louise Casey and other representatives of the charities involved also met Charles.
The event is a solo one for Charles, with the Queen, who had hoped to join him, still recovering from a nasty chest infection.
For his birthday, gun salutes will be fired in Green Park by The King's Troop Royal Horse Artillery and at the Tower of London by the Honourable Artillery Company.
Bells will also be rung at Westminster Abbey where the King was crowned in 2023.
Yesterday, Charles hosted a special celebrity reception at Buckingham Palace in honour of the UK's film and television industry.
The King, in black tie, walked the red carpet on the eve of his birthday, meeting stars Denzel Washington, Paul Mescal and Pedro Pascal at the glitzy global premiere of Gladiator II.
Alongside Camilla, who attended for part of the event, he chatted with a host of famous faces including actors Damian Lewis, Emily Mortimer and Lucien Laviscount, and Gladiator director Sir Ridley Scott.
Charles also had a giggle as he met Kaitlyn Coleman, 7, and Sophie Alger, 4, who gave him a brochure and flowers.
The original Gladiator won five Oscars and grossed $465.4 million worldwide at the box office and renowned for Russell Crowe's infamous battlecry "are you not entertained".
The global premiere of Gladiator II was hosted jointly by Paramount Pictures and the Film and TV Charity.
It was the 72nd Royal Film Performance delivered by the charity, which marks its 100th anniversary this year.
Founded in 1924, the Film and TV Charity is dedicated to those who work behind the scenes in the UK’s film, TV, and cinema industries by supporting their mental health and financial well-being.
Charles, like his late mother Elizabeth II, has two birthdays, his actual one on November 14, and his official one, which falls on the second Saturday in June.
Since 1748, the monarch's official birthday has been marked by the parade known as Trooping the Colour, which was usually held on the king or queen's actual birthday.
Edward VII, who reigned from 1901 to 1910, was born in the month of November.
But he celebrated officially in May or June because there was less chance of it being cold and drizzly during the outdoor event.
Charles's grandfather George VI, who was born in December, reintroduced the idea, and the late Queen Elizabeth II continued it, as has the King.
Prince Charles Philip Arthur George was welcomed into the world on November 14 1948 at Buckingham Palace, the first child of the future Queen Elizabeth and Prince Philip, the Duke of Edinburgh.
As the Prince of Wales, he was the nation's longest serving heir to the throne, and he became King on September 8 2022 on the death of his mother, the late Queen.
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News of Charles' cancer, undisclosed in its form, came in February, after it was discovered while he was treated in hospital for an enlarged prostate in January.
He cancelled all face-to-face public duties but returned in April and has since travelled to France for D-Day commemorations, hosted an incoming state visit for the Emperor of Japan, and undertaken a recent hectic tour to Australia and Samoa with the Queen, despite still undergoing outpatient cancer treatment.