Martin Kemp, an emeritus professor at the University of Oxford, is one of the foremost experts on Leonardo Da Vinci. He has recently worked on a translation and collation of the Codex Leicester and he talks Dan through Leonardo's most interesting and prescient ideas. Producer: Peter Curry
Dan talks to Simon Sebag Montefiore about the letters that changed the course of history.
Every day, ten thousand Americans wrote to Obama. Jeanne Marie Laskas tells their story, and the profound impact that these letters had on the President.
Betty Webb was heavily involved with the work going on at Bletchley Park. While she was not part of the code-breaking team, her work was invaluable to the success of Bletchley, and Dan talks to her about her life and wartime experiences.
