Guarding Diana -

Diana, Princess of Wales -- security code name 'Purple Five Two' -- travelled all over the world during her incredible life. Wherever she went, in public or in private, she was shadowed by her Scotland Yard personal protection officer, Inspector Ken Wharfe, whose job it was to keep her safe, even to the extent of sacrificing his own life, if necessary. The SAS-trained officer from the Yard's elite Special Operations 14, Royalty and Diplomatic Protection Department, was with the Princess every step of the way. As she dazzled among Washington society or walked the sand of exclusive Caribbean beaches he watched over her. In the foothills of the Himalayas, the heat and dust of India and the heart of Africa, he was always just a heartbeat away. In the six years that Ken was at Diana's side they travelled hundreds of thousands of miles together, sharing secrets, laughter and tears on a truly extraordinary journey. This is their story.