Prince Harry quipped that his brother William will be envious that he has managed to escape from a "screaming" Prince George.
Speaking as he prepares for a 200-mile polar trek in Antarctica, Harry said, "I think he's just quite jealous I managed to get away from a screaming child."
More top news
The pensioner, who is in her 70s, says her daughter has suffered from Huntington's disease.
US singer John Legend said he was "moved" by footage of the teenager singing one of his songs.
John Noakes was Blue Peter's longest-serving presenter.