The Duke of Cambridge has said he wants the Prince of Wales to spend more time with his grandchildren because “when he’s there, he’s brilliant”.

William suggests in a BBC documentary that he has been “working” to get his father to see Prince George, Princess Charlotte and baby Prince Louis more often.

In Prince, Son And Heir: Charles At 70, the duke is asked if Charles has time to be a grandfather on top of his other work, and replies: “It’s something I’m working more heavily on, put it that way.

“I think he does have time for it, but I would like him to have more time with the children.

William and Charles
William and Charles (Jane Barlow/PA)

“I think, he’s reached his seventieth year, it’s a perfect time to consolidate a little bit because as most families would do, you are worried about having them around and making sure their health’s OK, 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, you know, play around with the grandchildren. Because when he’s there, he’s brilliant, but we need him there as much as possible.”

The Duchess of Cornwall also paid tribute to Charles’s role as a grandfather, saying her five grandchildren “absolutely adore” the prince, who can read the Harry Potter books while doing the voices of the characters.

The documentary features a touching picture of the prince cradling his grandson Louis, and in another photograph he is seen swinging around a little girl thought to be one of Camilla’s grandchildren.

In the documentary, Charles’s immediate family paint a picture of the heir to the throne as a compassionate man who wants to help those around him, but is driven to achieve these aims.

His son the Duke of Sussex says: “He does need to slow down, this is a man who has dinner ridiculously late at night.

“And then goes to his desk later that night and will fall asleep on his notes to the point of where he’ll wake up with a piece of paper stuck to his face.”

This image of a relentlessly working prince is something that was evident when his sons were boys, Harry adds, saying: “The man never stops. I mean when we were kids, there was bags and bags and bags of work the office just sent to him.

“We could barely even get to his desk to say goodnight to him.”

Prince, Son And Heir: Charles At 70 will be screened on Thursday at 9pm on BBC One.