Robert claimed that Her Majesty was miffed to learn Wills had been boasting about how he would change the monarchy when eventually became King, Express reported.
“Her Majesty was not impressed by her grandson's noisiness, which got worse as Harry became old enough to join in,” Robert claimed.
He went on to allege that the behaviour resulted in fighting, crying and boisterous running around whenever the heir and spare visited Windsor, Sandringham or Balmoral.
“It was poor behaviour that [the Queen] did not expect of her grandchildren,” Robert alleged.
“Elizabeth II made some enquiries and was particularly horrified to learn that one of William's favourite lines ran 'When I am king, I'm going to make a new rule that...’”
Despite claims of unruly behaviour, William appears to using his title for the greater good, with the prince seemingly following in his father’s sustainable footsteps.
Speaking in the new ITV documentary, Prince William: A Planet For Us All, the 38-year-old urged people to acknowledge the growing environmental threat to the planet.
“I’ve always loved nature… but fatherhood has given me a new sense of purpose,” William says in the first-look promo.
“Now I’ve got George, Charlotte and now Louis in my life, your outlook on life does change. You want to hand over the wildlife in a much better condition,” he added.
The documentary, which was filmed over the last few years, follows Wills’ travels in Tanzania and Pakistan, where he identified the effects of climate change.