Methods used to get info

A combination of three methods was used to gain secrets from German prisoners.

The first was interrogation to see what the prisoner was willing to give away of his own accord. If the prisoner had technical knowledge of the workings of a U-boat, or torpedoes, for example, he was asked to sketch the equipment and label the parts.

The second method was use of the M Room where the prisoners' conversations in the cells were secretly recorded for information which they had failed to tell the interrogator. It was found that the prisoners spoke freely to each other because they did not realise that anyone was listening to them.

The third method was the use of stool-pigeons. These were men who pretended to be real prisoners and were placed in a cell to encourage the cellmate to talk. It was found that the most successful method was a combination of the M Room and use of stool-pigeons.