Dan talks to Joanne Freeman about the history of polarisation in the USA, giving an extraordinary insight into the tone of American politics' early days.
Frances Welch has written for the Sunday Telegraph, Granta, The Spectator and the Financial Times. She is author of Rasputin: A Short Life.
Calder Walton talks to Dan about Russian interference in past elections.
Dr Sue Black is a British computer scientist, academic and social entrepreneur. She has been instrumental in saving Bletchley Park, the World War II codebreaking site. Her book documenting this vital task is 'Saving Bletchley Park: How #SocialMedia Saved the Home of the WWII Codebreakers'.
