Once upon a time, there was a little girl. She was fair-haired, pretty and perhaps slightly chubby. She had two far-from-ugly older sisters and an adorable little brother. She lived in a big house and had a loving but distracted father. Her mother had gone away. The little girl’s name was Diana.

          She went to school, like all little girls, but the prizes she won were not for scholastic achievement but for kindness and care for others. Her closest relationships were the ones she nursed with pets and those she might have dreamed of hen she slipped into the solitary harmonies of music and dance.

          The little girl grew up and became a princess. All the hopes and doubts of her troubled childhood were respectively realized and vanquished on a magical day in 1981 when she married the Prince of Wales. But all fairy tales have a subtext and a dark side: Mary Clarke is uniquely placed to write that of Diana Spencer.

          Only Mary Clarke, Diana’s nanny and companion during the troubled period of her parents’ divorce – a time which coincided with Diana’s adolescence – could write with such authority of those years. The child was growing towards womanhood amidst family tensions which have marked her forever. In the school holidays – bundled from mother to father after her parents’ acrimonious divorce -Diana’s rock was Mary Clarke who writes here with perception, humour and clarity about her caring for others, her craving for stability and the seeds of her eating disorder. Only Mary Clarke, a trusted friend of the Princess, saw how Diana dealt with the upheavals. Her observations lend greater understanding than any outsider into Diana’s character development and personality.

          Mary Clarke, criticized by Diana’s mother and a pivotal witness in the High Court case which resolved that Earl Spencer should retain custody of his children, knew Diana as well as anyone during that crucial and critical time. She writes with honesty and affection.

          Once Upon a Time is the most illuminating book yet written about the Princess of Wales.