The Duke of Cambridge, who was 15 when Diana was killed in the road accident, turned to his brother, Prince Harry, for support instead of shedding tears publicly because he has "the Windsor ability to keep his emotions hidden", the book says.
"At 15, William was no longer a young boy, but not yet a man; it was a difficult age. He didn't speak to Sandy about his feelings, and she never saw a tear; he appeared to internalise his grief, just as he'd internalised so much in his life already.
"William, who has the Windsor ability to keep his emotions hidden, appeared to be remarkably controlled," author Penny Junor writes in the new biography 'Prince William: Born To Be King' which draws on the recollections of Sandy Henney, the Prince Charles' press secretary.
Henney said of the Duke, now 29: "I think he has an innate sense of self-protection. If you ask him a personal question, he will be as honest as he wants to be, but you will never get down into the real root of William because that