Sidney George Reilly MC (1873 ¡V 1925) known as "Ace of Spies". Russian-bornventurer and secret agent employed by Scotland Yards Special Branch and later by the Foreign Section of the British Secret Service Bureau, the precursor to the modern British Secret Intelligence Service (MI6/SIS). He is alleged to have spied for at least four different great powers, and documentary evidence indicates that he was involved in espionage activities in 1890s London among Russian ?migr? circles, in Manchuria on the eve of the Russo-Japanese War (1904¡V05), and in an abortive 1918 coup d?tat against Vladimir Lenins Bolshevik government in Moscow.