![The National Archives Podcast Series show](https://d3dthqtvwic6y7.cloudfront.net/podcast-covers/000/028/765/small/the-national-archives-podcast-series.jpg)
Summary: Professor Christopher Andrew, formerly official historian of MI5 and author of 'The Defence of the Realm: The Authorized History of MI5', introduces key files from the release of Security Service files to The National Archives in August 2015.