The Queen, Prince Charles and the royal family before them have all spoken in clipped, posh tones of “received pronunciation”. Prince William and Harry are among those who speak in a much more relaxed style than their older relatives.
“Kate has focused on her voice. She always strikes me as more careful. They are both clearly RP but given that he is a royal and she isn’t, you would expect him to be posher, but I’m not sure he is.”