The Prince reportedly loves spending time with his grandchildren George, Charlotte, and Louis, and will happily "get down on his knees and crawl about with them for hours, you know making amusing noises and laughing", the Duchess says in the documentary.
She said: "We worked quite a lot with the Prince of Wales, who has incredible taste in specifically classical music, so it was really fun to spend some time going through selections with him".
With The Prince of Wales' 70th birthday approaching on November 14, it's understandable why these brothers want their dad - who already has three grandkids and another one on the way - to put work on the back burner for a bit. "You only have to look at Shakespeare plays, "Henry V" or 'Henry IV, Part 1 and 2, ' to see the change that can take place - because if you become the sovereign, then you play the role in the way that it is expected", the heir insisted.
"If life dey show you pepper, make pepper soup", he said, which roughly translates to "life is what you make it".
"As I am sure you will all agree, "If person too tey for party, e go follow dem wash plate".
Charles' wife, Duchess Camilla, admitted it was a "touching" moment, which she only witnessed when she watched the wedding back on television.
Asked what advice she would like to give him for his 70th birthday she adds: "My Father once said to me, 'As you get older, you've got to do one thing and that is pace yourself".
During the wedding, Prince Harry adorably thanked his beloved "pa" for walking Meghan down the aisle at St. George's Chapel.
"I think it's vital to remember there's only room for one sovereign at a time, not two".
"It's the things he does behind the scenes that people don't know about". And he adds "I do realise that it is a separate exercise being sovereign".
Lord Hain, who welcomed his "regular interactions" with Charles when he was a cabinet minister, said of Charles's comments: "I don't think we expect the monarchy to be either stony-faced silent or to have no views".