In 2015 documentary Serving the Royals: Inside the Firm, Parry revealed fascinating insights into the royal household.
He said: “You are a servant to people of higher calling and you have to behave in a subservient manner.
“Staff weren’t allowed to walk down the centre of the carpets because we would wear them out.
“The central part was of course restricted for the Royal Family.”
Parry also recalled how he was once told off for breaking china, but claimed he never got yelled at quite like a fellow aide who fumbled a task he was assigned by Princess Anne.
Mr Parry said: “She looked at him and said: "You incompetent t**t!!"
Princess Anne is the second child and only daughter of Queen Elizabeth and Prince Philip.