Ralph Tester

Ralph Paterson Tester (2 June 1902 – 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).

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.

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.

Recruited to Bletchley Park, and during later 1941 was the head of a small group working on a double Playfair cipher used by German military police. Testery set up in July 1942 under Major Ralph Tester and the three other original founding members, cryptographers and linguists were: Capt. Jerry Roberts, Peter Ericasson and Maj. Denis Oswald, all four were fluent in German. The Testery used hand methods, working on a German hand cipher to break messages enciphered on TUNNY Fish (cryptography) traffic. Messages broken by hand reached 1.5 million places within one year of its foundation. By the war’s end in May 1945, the Testery had grown to nine cryptographers, out of a total staff of 118 organised in three shifts.

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