Double Agent Balloon Dickie Metcalfe's Espionage Career for MI5 and the Nazis

Recently cashiered from his infantry regiment, he had an ulterior motive - by supplying MI5 with tidbits of information about weapons and arms deals in his newfound profession as an arms dealer, he hoped they would be able to help him get his commission reinstated. Metcalfe became BALLOON, a sub-agent of double agent TRICYCLE's Yugoslav spy ring.
Concurrent with his spying activities, he collaborated with the co-inventor of the Bren gun to develop a new submachine gun for British forces. After the war, he was also a celebrated motor racing driver and continued to compete until shortly before his death. His success as a double-cross agent in the eyes of both his masters - British and German - is examined in this book, using official documents as a primary source.