The Intelligence Corps is one of the smallest and most secretive elements of the British Army. It has existed in various guises since the early 20th century, but it was only formally constituted in July 1940. In this book, Michael Ashcroft tells the astonishing stories of some of its most courageous and ingenious figures, who have operated all over the world from the First World War to the present day. Whether carrying out surveillance work on the street, monitoring and analysing communications, working on overseas stakeouts, receiving classified information from a well-placed contact or interrogating the enemy in the heat of war, a hugely diverse range of people have served in the Corps, often supplementing their individual professional skills with original thinking and leadership in the name of the Crown. This book pays tribute to them.