The Countess of Wessex has joked about holding up the Queen's state banquet speech and the "terrifying" experience of attending the formal dinners in a documentary charting the Diamond Jubilee year.
In her first television interview since becoming a royal, Sophie described how she will never forget the "look" the monarch gave her as she watched her daughter-in-law delay proceedings as she tried to find her seat.
The ITV documentary called Our Queen chronicles the major events, both at home and abroad, that marked the 60-year reign of the monarch and features interviews with members of the royal family and senior figures.
The Duke and Duchess of Cambridge appear to have a competitive streak according to one Olympian who was interviewed for the film which is screened on Sunday evening.
Boxer Anthony Ogogo, who won a middleweight bronze medal at London 2012, spoke during a Palace reception, held last October for Olympians and Paralympians, soon after meeting Kate. He said: "When William and Kate play scrabble they don't usually finish it - because one of them slams it shut."
Speaking about state banquets, Sophie said in the documentary: "The moment you go into the ballroom at Buckingham Palace - actually it's terrifying - because you just see a wall of people and you then think 'oh help, I've got to find my chair'.
"Because I'm normally walking in with somebody who's never visited before, they don't know what they're meant to be doing and I have to say on more than one occasion I've managed to sit in the wrong seat."
Sophie added laughing that once the Queen spotted her dilemma trying to find the right seat: "But I shan't forget the look that I got when I couldn't find my chair and she was looking to do her speech - I decided I might study the notes a little more carefully next time."
London 2012 chief Lord Coe revealed he was concerned about the Olympic opening ceremony - where the Queen appeared to skydive into the main stadium - descending into "it's a royal knockout".
But he said when the footage was played on screens he could hear "two princes" behind him - the Duke of Cambridge and Prince Harry - shouting "go granny".