Beginnings

The M Room was a major part of Britain's secret war against Nazi Germany.

Churchill believed that enemy prisoners-of-war were the most valuable asset in wartime. They were the source of the enemy's secrets. But how to get the information out of them? British Intelligence came up with the idea of bugging the conversations in their cells. The cells were located in three stately homes which were requisitioned by British Intelligence and wired with the latest bugging devices and recording equipment.

This highly top-secret unit was called the Combined Services Detailed Interrogation Unit (CSDIC). It pretended to be a supply depot, but its obscure name was a mask for its real activities. The prisoners had no idea that they were being overheard and spoke freely to each other, and gave away lots of important information and secrets about the war in the air, at sea and on land.

Alongside the codebreaking work at Bletchley, the M Room intelligence enabled Britain to win the war. It was a very clever way of spying on the enemy.