With Britain in Mortal Danger-Second Edition: Britain's Most Secret Army of WWII

In 1938 the War Office ordered the Director of Military Intelligence to create a unit that would research the tactics and organisation needed in the event of an invasion. After Dunkirk Lt Col Holland's Military Intelligence (Research) expanded greatly, secretly recruiting civilians and service personnel thought suitable for subversive and irregular warfare. Although never called upon, their story remained shrouded in secrecy for half a century.