One day after lunch the Queen Mother stood up at the end of the table, clicked her fingers the way Ali G does, and said to the Queen: "Darling, lunch was marvellous - respec."
They went on to say that their grandmother "had a young sense of humour" and "loved a good laugh, even if the joke was about her."
Enjoyed a good giggle
William also said she sometimes found the more serious side of being a member of the royal family funny, saying: "Anything that was meant to be formal and went wrong, she enjoyed. She would have a good giggle."