On the day of King George VI's coronation, his daughter Margaret is said to have asked her elder sister Elizabeth: "Does that mean you will have to be the next Queen, Lilibet?". "Yes, some day", Lilibet replied. "Poor Lilibet", said Margaret. Lilibet's upbringing was extremely sheltered - cocooned in Victorian formality, her tutors and playmates carefully selected by zealously protective parents. Yet by the age of 15 she was "doing the boxes" and discussing political issues with her father, the King. Elizabeth became Queen at the age of 26. The expression of composed gravity she wore at her coronation has changed little since. In the subsequent decades of unceasing public appearances, she has never been seen to shed a tear openly. Her reign has so far spanned the successive terms of office of eight prime ministers and eight American presidents. Although one of the world's most closely-scrutinized women, she remains inscrutable, but is still the stabilizing force of her dynasty and the guardian of its survival in rapidly-changing times. This is a biography which is also about the people and problems surrounding the Queen - the courtier class, with its self-perpetuating, self-protecting mechanism, and the sizeable staff who make the monarchy work and maintain the trappings of power; the relationships between Church and State, the Throne and Parliament; her special link with the Commonwealth; and, not least, her enduring marriage. The author first met Queen Elizabeth when he was a teenager in Malta, and later covering royal tours and on assignment for "Time" magazine in London. His previous books include "Scarlett, Rhett, and a Cast of Thousands".