"Robert Lacey, author of A Brief Life of the Queen, says she would have been prepared for the news, even if her father's death from a coronary thrombosis was a shock.
"Her private secretary carried sealed envelopes containing a draft Accession Declaration. She was ready but it was a secret that was shared with few people."
It is said that she reacted stoically, and showed little immediate distress. "She was sitting erect, fully accepting her destiny," Martin Charteris is quoted as saying in Lacey's book. No-one saw any tears."