Buckingham Palace has announced the King is taking on the role of The Ranger of Windsor Great Park, a post previously held by his father, Prince Philip.
The King will be spending his birthday privately, with no official engagements planned.
Charles spent the day ahead of his 74th birthday leading the nation in honouring its war dead during the annual Remembrance Sunday service at the Cenotaph.
His floral tribute to the fallen left at the memorial in Whitehall featured the words ‘In memory of the glorious dead. Charles R’.
Last November he celebrated his birthday by releasing a photo of him sitting on a bench in Highgrove, as the Queen faced another health scare.
Last week the King was targeted with four eggs during a visit to unveil a statue in honour of the late Queen at York Minster.
Military celebrations are marking the day, with the Band of the Household Cavalry playing Happy Birthday outside Buckingham Palace during the changing of the guard ceremony.
Gun salutes are also being fired across London, with the King’s Troop Royal Horse Artillery firing 41 rounds from Green Park.
The role of Ranger offers oversight and guidance to the deputy ranger and his team in the day-to-day stewardship of one of the country’s oldest landed estates.
Paul Sedgwick, The Crown Estate’s managing director, rural and deputy ranger of Windsor Great Park, said: ‘We are honoured to have His Majesty as Ranger of Windsor Great Park, continuing a long tradition of the Sovereign and members of the Royal Family holding this role.
‘Windsor has a wonderful heritage with many precious natural habitats.
‘His Majesty’s passion and commitment to the natural world will be invaluable as we seek to become a centre of excellence for environmental best practice, preserving and enhancing the Great Park for generations to come.’
