Who were they?

For the first three years of the war, the secret listeners were British Intelligence Officers who had an excellent knowledge of German, often because they had a university degree in German. However, these secret listeners often found it difficult to understand the prisoners' dialects of the and the extremely technical language being used in the conversations. Commanding Officer Kendrick decided that he needed native Germans for this work. He looked to the British Army's labour unit, the Pioneer Corps, where around 3,000 German and Austrian refugees from Nazism were carrying out manual tasks for the war effort. A hundred of them were transferred to the M Room to become the new secret listeners. They signed the Official Secrets' Act and swore never to talk about their work to anyone for 50 years. They were mainly Jews, but also political opponents, who had had to flee the country of their birth because of Hitler's racial persecution. They had the greatest motivation to defeat the Nazis and were now trusted with some of Britain's most important wartime secrets.