It became apparent very early on during World War I that aerial photo-reconnaissance and photo-interpretation would become essential tools for British intelligence. Yet the highly successful techniques declined during the inter-war period, kept alive only by private individuals and a few devotees in the armed forces. They were rapidly restored, however, during World War II and developed until they became remarkably effective methods of obtaining accurate sources of intelligence for Allied commanders when making strategic and tactical decisions. Since then, Britain has not entered any conflict before ensuring that these techniques played a prominent part. This text traces the development of photo-reconnaissance skills from the earliest days to the present and includes such conflicts as the Falklands War and the Gulf War. It is based on official and personal records and was written in collaboration with experts with detailed knowledge of the subject. The text includes over 400 photographs from many types of aerial camera and all major types of photo-reconnaissance aircraft. Many of the photographs were taken in action and all appear with detailed captions.