Details of the troubled relationship between the Queen and Princess Diana have been outlined in the new book: 'The Queen's Speech: An Intimate Portrait of the Queen in Her Own Words'.
According to the book, the Queen thought Diana was a "child" and "didn't know how to handle her."
Author Ingrid Seward details the troubled relationship between Diana, who was just 20 when she married Prince Charles in 1981, and her mother-in-law.
Seward claims the two had been close initially but drifted apart as the years passed, and this frustrated the Queen.
As Diana's unhappiness mounted and her marriage to Charles unravelled, the monarch found herself at odds with her increasingly unhappy daughter-in-law.
"The Queen was desperate to help Diana but she just didn't know how," says Seward. "And Diana couldn't connect with the Queen."
Diana broke down in front of the Queen
Seward, who is editor-in-chief of Majesty magazine, writes: "She just broke down (crying) in front of the Queen and no one had ever done that before in her life. She just didn't know how to handle this emotional young woman. She was really just a child."
Years after, in August 1997, when the Queen was told that Diana had been in a car accident, Seward writes that the monarch responded: "Someone must have greased the brakes."
"It is a very old-fashioned, English saying," says Seward. "It is the sort of thing people said if someone went down the hill and had an accident. Her very first reaction was, 'Oh my God, someone has tampered with the car.' She obviously very quickly knew it wasn't true."