Paul Lay and Alastair Benn are joined by Calder Walton, author of Spies: The epic intelligence war between East and West, to discuss how governments can use covertly acquired intelligence as a powerful tool to influence debate — and how easily it can all go wrong.

Image: US Ambassador to the United Nations, Adlai Stevenson, second from right, confronts Soviet delegate Valerian Zorin, first on left, with a display of reconnaissance photographs during an emergency session of the U.N. Security Council at the United Nations headquarters in New York, on October 25, 1962. Credit: Associated Press / Alamy Stock Photo