British Secret Listening Operations

British intelligence developed a covert system for listening to German prisoners who believed that their private conversations were secure. Microphones and hidden listeners were used to capture discussions that often revealed information prisoners would not provide during formal interrogation.

The system expanded from experimental work at the Tower of London to specialist sites including Trent Park, Latimer House and Wilton Park. Senior German officers and other prisoners discussed weapons, operations, morale and war crimes, creating a large body of intelligence material.

Thomas Kendrick played a central organisational role in these operations. Helen Fry’s The Walls Have Ears is a history of the listening programme, while Spymaster places it within Kendrick’s longer intelligence career.