Prince William has urged his workaholic father to relax as he turns 70, so he can spend more time with his grandchildren.
The Duke of Cambridge, who has three kids – George, five, Charlotte, four and six-month-old Louis – said: “It’s something I’m working more heavily on, put it that way.
“I would like him to have more time with the children. Now he’s reached 70, it’s a perfect time to consolidate a little, because as most families would do, you are worried about having them around.
“And he’s the fittest man I know but equally I want him to be fit until he’s 95, you know, going on.
“So, having more time with him at home would be lovely, and being able to play around with the grandchildren. Because when he’s there, he’s brilliant.”
Charles has admitted he will be forced to change his “meddling” ways when he is king.
In a documentary to mark his 70th birthday on Wednesday he has spoken for the first time about what type of king he is likely to be.
Asked about his “meddling” in issues such as climate change and planning, he said: “I always wonder what meddling is.
“I mean I always thought it was motivating. I’ve tried to make sure whatever I’ve done has been non-party political. It is vital to remember there’s only room for one sovereign at a time, not two.
“So you can’t be the same as the sovereign if you’re the Prince of Wales or the heir. The idea I’m going to go on in exactly the same way, if I have to succeed, is complete nonsense.”
Until he becomes king, Charles, the longest-serving heir to the throne in British history, will continue to speak his mind.
But he said: “I’m not that stupid. I do realise that it is a separate exercise being sovereign. So of course, you know I understand entirely how that should operate.
“I won’t be able to do the same things I’ve done as heir. Of course you operate within the… the constitutional parameters.”
Charles also urged son William to find his own path when he becomes the Prince of Wales.
He said: “Each one of my predecessors had to find out how they would do it – a lot of them dropped dead or were killed before they got very far.”
A BBC crew followed Charles for almost a year for the one-hour documentary by John Bridcut, which to be shown on BBC1 tonight at 9pm.
Mr Bridcut said: “He’s got amazing energy. He has so many balls in the air at any one time, it’s incredible.”
The Duchess of Cornwall says Prince Charles is so driven to succeed that it is like “he would like to save the world”.
Camilla described her husband as “a very exceptional man” who reads Harry Potter books in funny voices to her grandchildren.
She said: “I would like a lot of people to see the lighter side of him.”
But she admitted his dedication to causes such as his Prince’s Trust charity, and his work with the environment and climate change, can be to his detriment.
She said: “He feels everything inside, that’s why he gets things done. He’s pretty impatient. He wants things done by yesterday as I think everybody who works for him will tell you. But he’s driven by this passion inside him to really help.”
Prince Harry praised his father for stepping in to walk wife Meghan down the aisle after her dad was too ill to attend their wedding.
Harry said: “I asked him to and I think he knew it was coming and he immediately said, ‘Yes, of course, I’ll do whatever Meghan needs and I’m here to support you.’”
Harry, 34, also urged Charles to relax his workload. Harry said: “He does need to slow down. This is a man who has dinner ridiculously late at night.
“And then goes to his desk and will fall asleep on his notes to the point of where he’ll wake up with paper stuck to his face.
“He never stops. I mean, when we were kids there was bags and bags and bags of work. We could barely even get to his desk to say good night to him.”