Ralph Paterson Tester (2 June 1902 – May 1998) was an administrator at Bletchley Park, the British codebreaking station during World War II.
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.
[3]: 250 On the outbreak of war, he worked for the BBC Monitoring Service which listened in to German public radio broadcasts.
[4] 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.
"[3] Towards the end of the European war, Tester was part of a TICOM team, a mission sent to Germany to discover information about their communications technology, including TUNNY machines.