Following the outbreak of war in 1939, the British Intelligence Services needed a school to train agents to be infiltrated behind enemy lines in occupied Europe. Brickendonbury Manor was requisitioned and run by the Secret Intelligence Service’s D Section. They already had training schools in Palestine. With the formation of the Special Operations Executive in July 1940, they took over the training and Brickendonbury specialised in sabotage. George Rheam, described as the father of industrial sabotage, and fellow instructors prepared a handbook which was used by SOE trainers in similar schools overseas. Bernard O’Connor, author of numerous books on World War Two sabotage, provides a detailed foreword.