Alan Turing was one of the most influential people in science or mathematics in the twentieth century. He laid the theoretical groundwork for computing and helped the Allies win World War II by breaking the Egnima code. He also made fundamental contributions to pure mathematics and to the development of programming languages, neural nets, and artificial intelligence.
In 1939, he was asked to join the Government Codes and Cypher School, which was moved to Bletchley Park when war was declared on 3rd September. Alan moved there next day and lodged at the Crown Inn at Shenley Brook End for much of the war.