A letter from Secret Service head Sir Vernon Kell to the Chief Constable of Hull prompted an MI5 investigation into Jacob Bronowski, one of Britain's most renowned academics, it was revealed this week.
Secret papers released by the National Archive showed that Sir Vernon wanted Professor Bronowski, considered by MI5 to be a "Communist intellectual," shadowed while he worked at University College, Hull, just after the start of the war. Agents considered him to be "an extreme leftist" and to be espousing "anti-British views".
Even after a Special Branch report said he was a Labour Party member, another police officer described the Polish-born Professor Bronowski as "a Communist in everything but name".
But the professor later became scientific adviser to the Ministry of Works, then director of research at the National Coal Board. He was also a successful broadcaster, best known for the documentary series The Ascent of Man.
Another well-known Jewish personality, Larry Adler, was reported in 1951 to have been a member of the American Communist Party and to have been involved in several organisations investigated by the California Committee on Un-American Activities.
MI5 opened a file on the harmonica virtuoso, with one official noting that if he were allowed to settle in the UK, "the Communist Party would make every effort to exploit his name as an entertainer." He remained on file until 1958.