In my first semester of college, when I took Western Civ,I had had to read one of my first really grown-up history books, The European Witch-craze of the Sixteenth and Seventeenth Centuries (an intriguing topic). Now, all these years later, I've read his biography. He's best known for his The Last Days of Hitler, the result of investigation he did immediately after the war for British intelligence. This journalistic endeavor boosted him immensely, and then he went into the history business at Oxford, and later Cambridge. He never wrote the big book, but he was the master of the essay. Alas, while Hitler made his career, the topic also caused him great grief when he mistakenly (and to his credit, preliminarily) authenticated Hitler diaries that were a fraud.
I enjoyed book. For a better reviews (and there are many), go here or here. A well-written biography of an interesting character (as interesting as an academic historian can be!).