Introduction

When and why did espionage become professionalized? How did agents keep tabs on people in a time before high tech? And how have animals been used for spying? Those are just some of the questions that you sent to us to answer. Our expert is michael goodman, professor of intelligence and international affair s at king's college london. Putting the questions to him was our digital editor, eleanor evans. For to day's everything you wanted to know about episode.