In 1934, he was founder of the Progressive Film Institute. After the war, Montagu worked as a film critic and reviewer. Montagu had a keen interest in wildlife conservation, and was a council member of the Fauna Preservation Society for several years. He was friends with the eminent Soviet conservationist and zoologist Prof. . He had contacts in Mongolia, and was a champion for the conservation of the endangered Przewalski's horse. On 10 January 1927, he married Eileen Hellstern (1904–1984), the daughter of Francis Anton Hellstern, a boot maker from Camberwell. Although the couple did not have any children together, Ivor adopted Eileen's young daughter, Rowna Barnett, née Hellstern (1922–1996). Table tennis Montagu was a champion table tennis player, representing Britain in matches all over the world. He also helped to establish and finance the first world championships in London in 1926. Montagu founded the International Table Tennis Federation that same year, and was president of the group for more than forty years, not retiring until 1967. He helped expel apartheid South Africa from the Federation during the 1950s. He also founded the English Table Tennis Association (ETTA), and served several terms as chairman and president. Montagu was inducted into the International Table Tennis Foundation Hall of Fame in 1995. Recruited by Soviet intelligence His older brother Ewen Montagu, a barrister in civilian life, became a Naval Intelligence Officer during the Second World War, privy to the secrets of top-secret Ultra and the mastermind of the successful deception that launched the invasion of Sicily, Operation Mincemeat. He later wrote a best-selling account of that adventure, The Man Who Never Was. Ivor Montagu himself turned out to be working, albeit briefly, for the other side. A 25 July 1940 cable from Simon Davidovitch Kremer, Secretary to the Soviet Military Attaché in London, identified him as the somewhat reluctant new recruit who was supposed to create an "X Group" of like-minded friends. By the following year, Hitler had invaded Russia and the Soviet Union became an ally of Britain's, so that by June, 1941, both brothers were technically working for the same side. Ivor knew of his elder brother's intelligence work, but it seems doubtful his brother knew of his. Counter-espionage agents at MI5, however, even Ewen's boss John C. Masterman, seem to have suspected Ivor in general because of his outspoken Communist politics, his hanging around with scruffy Russians and housing