But afterwards, he went out to gather mushrooms and clear his with Camilla and three members of staff by his side so his sister, Princess Anne, and others, could spend time with the late monarch.
Hardman alleges that the King was driving back to the castle when a member of staff called him “Your Majesty” and he found out about his mother’s passing.
He writes: “There was no question of waiting for the car to pull up at Balmoral. Imagine if there had been some accident or a hold-up along the way,’ explains one senior official.
“It was essential that the new King was told before anyone else. The Balmoral switchboard worked its way through a list of mobile phone numbers. Signals can be sketchy in rural Aberdeenshire and staff would usually have phones on silent while in attendance.
“Finally, one of the party felt their phone vibrating, recognised the number, answered and handed the phone to Sir Clive [Alderton, Charles’ principal private secretary].
“He had to ask his boss to pull over and stop. Sir Edward Young [Queen Elizabeth’s private secretary] was now on the other end of the phone. The new monarch knew exactly what was coming next.
“He had just turned off the B976 onto the back drive of the estate when, at the age of 73, he was addressed as ‘Your Majesty’ for the first time. No further explanation was needed.”
But the new King gave out a humble, heartbreaking reply.
According to Hardman, Charles replied softly “We’re nearly there.”
The book reads: “As the new Queen and the other occupants of the car immediately voiced their condolences, King Charles put the Land Rover in gear and drove on.”
Minutes later, Charles was greeted by a distressed Anne back at the castle.
