WORKAHOLIC King Charles writes up to 2,400 letters a year — around seven a day, The Sun can reveal.
Our non-stop monarch, 77, was even penning missives in the car on a Sunday morning as he was being driven to church.
As he stepped from his Lotus Eletre at St Mary the Virgin on the Sandringham Estate in Norfolk, stationery could be seen tucked into the pocket in the back of the driver’s seat.
The King is known to enjoy trying to reply in person to as many letters as possible sent to the royal household — a total of 101,669 in the last year.
He and Queen Camilla, also send birthday cards to the thousands of Brits who turn 100 every year.
A royal source said: “He’s a very thoughtful and considerate man and writes letters extensively to friends and contacts.
“He quite often writes to families impacted by major tragedies and loss of life of service personnel.”
Charles, who has been diagnosed with cancer, was awarded the hardest-working royal gong last year, dethroning the previous table-topper Princess Anne, his sister.
He conducted 535 engagements in 2025 which was 21 per cent of the entire public work carried out by the whole Royal Family over the year.
In addition to letter writing, Charles has been known for working extremely long hours his whole adult life.
In his memoir, “Spare”, Prince Harry said that, as boys, he and Prince William often found their dad “at his desk amid mountains of bulging post bags”.
He added: “More than once, we discovered him, face on the desk, fast asleep.
“We would shake his shoulders and up he would bob, a piece of paper stuck to his forehead.”
Charles and Camilla are set to begin their holiday in Scotland this month.