Mark Dunton is Principal Records Specialist at the National Archives, London, and has in-depth knowledge of researching public records, with a particular interest in 20th-century British political, social and economic history. Stephen Twigge is the former Head of Modern Collections at the National Archives, London. He was previously a historian at the Foreign and Commonwealth Office and has published a number of books and articles on the Cold War. Nick Harkaway is the bestselling author of eight novels, including The Gone-Away World, Titanium Noir and Karla’s Choice, the latest instalment of the George Smiley series created by his father, John le Carré.