This claim was brought forward by narrator Glynis Barber. In his documentary When the Middletons Met the Monarchy he claimed, “As a commoner, born into a middle-class home counties English family, Kate’s integration into the Royal Family hasn’t been easy.”
According to Express UK even royal author Robert Jobson chimed in to say, “[Kate and William] started dating, but very quietly.
No one knew very much about it, only their closest circle of friends. There’s talk that when Prince Charles was younger, his girlfriends used to call him ‘Sir’. I can’t imagine William would be anything like that.”