Spying may be one of the two oldest professions, but unlike the other one it has changed quite a lot over the years, and continues to do so.
During the quarter-century since the end of the Cold War, the main preoccupation of our intelligence agencies has not been with classic espionage by the Soviet Union, or with identifying new Philbys operating on their behalf. Espionage still goes on, but it is small beer compared to the terrorist threat that commands no less than 75 per cent of our agencies’ time and resources.
Stephen Grey takes us through the transformation in the recent past experienced by MI6, MI5 and GCHQ, as well as their counterparts in the United States. His central theme, however, is the essential requirement of human intelligence (HUMINT) if our agencies are to meet the demands and expectations imposed on them by politicians and the public.