The King and Queen are currently enjoying their summer break in Scotland, and were spotted at a church service last Sunday at Crathie Kirk.
Charles, 74, and Camilla, 76, who are believed to be staying at Birkhall, look set to welcome members of their family to Balmoral Castle in the coming days.
Today [Wednesday] marks the final day that the public can visit the grounds, gardens and exhibitions at the Castle.
The King's stay at Balmoral had been delayed slightly following his decision to reportedly extend its summer opening hours to the public.
The late Queen Elizabeth II would typically arrive at the estate in early August, where she would be greeted by a Pipe Band.
Through the years, the late Queen and the late Duke of Edinburgh played host to their children, grandchildren and great-grandchildren during their summer retreat.
Princess Eugenie has previously spoken of her fond memories about Balmoral telling ITV's documentary Our Queen at Ninety in 2016: "It's the most beautiful place on earth."
She added at the time: "I think Granny is the most happy there, I think she really, really loves the Highlands... Walks, picnics, dogs - a lot of dogs, there's always dogs! And people coming in and out all the time. Family-wise we're all there, so it's a lovely base for Granny and Grandpa to be - for us to come and see them up there, where you just have room to breathe and run."
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Charles is expected to follow in his late mother's footsteps and will likely be joined at Balmoral by the Prince and Princess of Wales and their three children, as well as the King's siblings, Princess Anne, Prince Andrew and Prince Edward, and their families.
Camilla is also grandmother to five grandchildren from her two children, Tom Parker Bowles and Laura Lopes, and they are also likely to join the royals this summer.
As per tradition, the King will host Britain's Prime Minister Rishi Sunak and his wife Akshata Murthy one weekend during his Scottish break.
Charles and Camilla will reportedly still be residing in Scotland for the anniversary of the late Queen's death on 8 September, where they will spend the day in private.
No public event is planned, and the couple will not hold a family gathering to mark the anniversary at Balmoral.
Queen Elizabeth II died at the age of 96 at Balmoral on 8 September 2022, after reigning for 70 years.
Her Late Majesty used to mark the passing of her father King George VI, who died on 6 February 1952, privately at her Sandringham estate.