MI5 Talks

In 1940, with London under attack and its Registry destroyed, MI5 moved to Blenheim Palace, the birthplace of Sir Winston Churchill. Known only as Box 500, Britain's counter-espionage service remained here until the end of the war.

Discover how the state rooms were transformed for intelligence work. The Long Library became a typing pool and the Great Hall filled with filing cabinets. Bound by the Official Secrets Act, the women who worked here supported operations such as the Double Cross System, which turned captured German agents into double agents ahead of D-Day.

Learn about the places where it happened, from the security checkpoint at Flagstaff Gate to the Nissen huts of Great Court and the Orangery, where weekly orchestra rehearsals offered a welcome break. You will also hear about secret trials on the lake, the family who lived alongside MI5, and the Soviet agent among its officers. There is no need to book, simply join us at Great Court on the day.