If you are a fan of the BBC series, MI5, then this is the book for you. The Defence of the Realm: The Authorized History of MI5 by Christopher Andrew is a must read. At just over 1000 pages, it’s a long read, but worth the effort. It’s more of a history lesson than it is a spy story.

The fascinating aspect of this book is to consider the unprecedented access that Andrew, a Cambridge University Professor of Modern and Contemporary History, had to the inner workings of the British Security Service. The book is divided into 6-parts ranging from the creation of the organizations foundation in 1909 up to its present day role of countering Islamic terrorism. Of particular interest is their dominant role played during the Second World War, armed with an astonishing understanding of Hitler’s objectives, in turning German agents.

Andrews recently spoke at a London School of Economics Public Lectures and Events forum to discuss the book that marks the centenary of the foundation of MI5. You can hear the podcast of that talk here. Of particular interest is the important role a sense of humor plays in the recruitment of an MI5 agent.

While unlike the series MI5, where all operations are solved in a 58:46 time frame, there are similarities between fiction and reality that will compliment each other if you watch the show and then read the book or vice versa. If you still can’t get enough, the official MI5 website is a treasure trove of information about the service.