Equipment

The M Room was a special room that was equipped with two stations, each with listening and recording equipment, and operated by six secret listeners-all men. A tiny bugging device was hidden in the light fittings of the prisoner's cell and wired back to the M Room. It enabled the monitoring of prisoners' conversations from the moment they woke in the morning until they went to sleep at night. As soon as the secret listener heard anything of interest, he set the recording equipment going and recorded it onto an acetate disc. Afterwards, the disc was played back so that he could write down the conversation word for word in German. This was then checked by another secret listener and translated into English. The written conversation was then handed to female intelligence staff to type up both the German version and the English translation.