Germany developed the V2 rocket and the Americans used the atomic bomb, but Britain's secret weapon in the Second World War is revealed today as that perennial schoolboy's favourite, itching powder.
In a neat dovetailing of the modus operandi of James Bond and Just William, Britain's undercover training network taught agents from around the world the best ways to get under the enemy's skin.
The Special Operations Executive issued an illustrated catalogue of "special devices" available for use by agents, including itching powder and explosive devices disguised as coal, bottles of Chianti or rats.
Some agents asked for itching powder and spread it on German soldiers' bedding, underwear and on contraceptives.
The catalogue also included a special powder that seized up machinery and was used in June 1944 by two French teenage sisters to delay rail transport of tanks badly needed by Germany in Normandy.
About 7,000 students passed through the training process, most of them from enemy-occupied countries. Schools were also set up in Singapore, Italy, India, Australia and Canada.
The basic syllabus used by the schools, reproduced in a book released today by the Public Records Office, taught students the psychology of a convincing disguise, how to slit the throat of a sentry silently and the secrets of invisible ink.Reuse content