Cracking the code was only half the battle. To keep the upper hand, when using Bill Tutte's statistical methods, the detailed counting had to be automated - enter Colossus! Professor Brailsford takes up the story. The professor's notes: Bletchley Park Playlist: Professor Brailsford used the book "Colossus" by B. Jack Copeland and others (Oxford University Press, 2006). Also recommended are chapters 18 and 19 from : "The Bletchley Park Codebreakers" by R. Erskine and M. Smith (eds.) Biteback Publishing 2011 This video was filmed and edited by Sean Riley. Computer Science at the University of Nottingham: Computerphile is a sister project to Brady Haran's Numberphile. More at