Ralph Tester

Ralph Paterson Tester (2 June 1902 – 1 May 1998) was an administrator at Bletchley Park, the British codebreaking station during World War II. He founded and supervised a section named the Testery for breaking Tunny (a Fish cipher).

Background The Lorenz cipher machine had twelve wheels, and was thus most advanced, complex, faster and far more secure than the three-wheeled Enigma. Lorenz was used to encipher top-secret messages between German Army H.Q. in Berlin, and the top generals and field-marshals on all fronts, including Adolf Hitler himself.

Career Before World War II, Tester was an accountant who had worked extensively in Germany and as a result was very familiar with the German language and culture. He held a senior position in the accountancy division of Unilever. On the outbreak of war, he worked for the BBC Monitoring Service which listened in to German public radio broadcasts.

Bletchley Park Tester was recruited to Bletchley Park, and during later 1941 became the head of a small group working on a double Playfair cipher used by German military police.

After the war, Tester returned to Unilever.