Now, to celebrate their grandmother's reign of 60 years on the throne, the two princes are giving rare and personal insight into what the 85-year-old queen is really like.
For one, Prince Harry, says the queen, seemingly a very independent woman, is, in fact, very dependent on her husband of more than 60 years, Prince Philip.
"Regardless of whether my grandfather seems to be doing his own thing," Harry, 27, told a BBC reporter, "sort of wandering off like a fish down the river, the fact that he's there, personally. I don't think that she could do it without him."
The princes' comments came in an interview with the BBC's Andrew Marr for a three-part documentary titled "The Diamond Queen" that will air as the queen celebrates her Diamond Jubilee, beginning Monday, Feb. 6. Excerpts of the interview were published in the Radio Times released in the U.K. today.
The interview with Princes William and Harry took place before their grandfather, Prince Philip, 90, underwent emergency surgery for a blocked coronary artery just before Christmas after complaining of chest pains.
"It's the first time a royal has ever said anything like this," Duncan Larcombe, royal editor at the Sun newspaper and ABC News contributor said of the princes' comments. "Perhaps that's a sign that the family are a little bit worried."
The queen's grueling schedule of travel, meetings and interactions with everyone from diplomats to commoners is also a constant worry for Harry.
Next Monday will mark her 60 years on the throne, "Yet she's carrying on and doing [the visits]," Harry says of his grandmother.
Buckingham Palace has not said what kind of public schedule Prince Philip will resume after his health scare, but plans had been for him and the queen to travel across the country to mark the Diamond Jubilee.
Prince William, recently married to Kate Middleton, and a constant target for paparazzi, reveals in the interview that he admires and has turned to the Queen for advice on how to lead a private life in the public eye.
"I think she doesn't care for celebrity … and she really minds about having privacy in general," William, 29, said.
It's "a very tricky line to draw between private and public and duty and I think she's carved her own way completely," he said. "She's not had a blueprint."