Very little has ever been written about Renato Levi, or his incomparable contribution to the Allied war effort, simply because his role has been kept so secret. Even with the declassification of MI5's wartime files, all references to his true identity were redacted. However, it is now possible to tell his astonishing story in full for the very first time since his death in 1954. As a double agent Levi, or 'Cheese' as he was codenamed, has few equals. He was an Italian Jew brought up in India, educated in Switzerland, and employed as a British agent while working for the French, Italian and German intelligence services. During his espionage career, which spanned the entirety of World War Two, he worked for four intelligence agencies simultaneously and miraculously survived the experience. He was imprisoned in Turkey and Italy, and his information, brilliantly fabricated in Cairo, had a profound impact on the course of the war in North Africa and the Eastern Mediterranean (he played a pivotal role in the Allies' recapture of Tobruk in November 1941), becoming the foundation upon which the concept of strategic deception was constructed. Levi was entirely cosmopolitan, a terrible womaniser, and the legitimate holder of a British passport. The huge quantities of misleading material that he conveyed to the Axis undermined the Afrika Korps' attempt to capture Cairo and the Suez Canal, and made a substantial contribution to defeating Rommel. As an agent of the British Secret Intelligence Service (MI6), he accomplished more, over a longer period, than any other. Quite simply, Levi became one of the most influential figures of the conflict, yet his role remains undisclosed until now.