Speaking to GB News, Charlotte Griffiths said: “His Majesty seems to be on the mend. I think it’s such a good sign that he was seen driving to Highgrove with the window down.

“It is a sign that he’s on the mend, and he obviously made a real point of winding his window down and waving to people.

Charles was seen in public on Friday for the first time since his brief hospitalisation the previous day. The King waved to crowds as he left his London residence at Clarence House by car.

He was photographed with his window down, acknowledging onlookers as he departed for Highgrove. This marked his first public appearance since experiencing temporary side effects from his ongoing cancer treatment.

Buckingham Palace confirmed on Thursday that His Majesty had required “a short period of observation in hospital” before returning home.

The monarch had been forced to cancel a string of engagements in Birmingham following the hospital visit.

Sources described the episode as a “most minor bump in a road that’s very much heading in the right direction”.

All indications overnight suggested that his health “continues on a very positive trajectory”, according to palace sources.

Griffiths suggested this health episode should remind the King to “slow down a bit” despite his determination to maintain a busy schedule.

“He does need to slow down a bit. So hopefully this is just the reminder he needs that he is going through cancer treatment,” she said.

When asked about the King’s workload, Griffiths noted that his cancer diagnosis initially “spurred him on to do as many things as possible”.

“But once in a while the body sort of tells you to slow down and stop,” she added.

Queen Camilla has reportedly been “nagging” the King to reduce his workload, according to Griffiths.

“Camilla will be happy because she’s always nagging him to slow down. She gets really frustrated by how hard he works and the fact he’s a workaholic,” she said.