They worked day and night during the second world war, deciphering Nazi messages, breaking Enigma codes and analysing top-secret military documents. But until now it was not known just how many of the intrepid female codebreakers who worked at Bletchley Park had studied at the same place, forming a hidden network of scholars who secretly changed the course of history. The names of the 77 alumnae of Newnham College – a women-only college that is part of Cambridge University – who were recruited to intercept, decrypt and translate military messages during the war have been revealed for the first time...