Why Spy? distills Brian Stewart’s seventy years of experience in intelligence. Few books currently available have been written by someone who has his practical experience both of field work and of the intelligence bureaucracy at home and abroad. Stewart relates successes and failures via a fascinating series of vignettes, either those cases in which he was personally involved, or seminal events such as the Japanese attack on Pearl Harbor, and draws conclusions that should be pondered by all those concerned with the limitations and usefulness of the intelligence product. Stewart also cautions against the tendency to abuse or ignore intelligence findings when their conclusions do not fit with preconceived ideas. He reminds the reader of the multiplicity of methods and organisations and the wide range of talents making up the intelligence world. The emphasis throughout Why Spy? is on the necessity of embracing a range of sources, including police, political, military and overt, to ensure that secret intelligence is placed in as wide a context as possible when decisions are made.