Hobsbawm joined the "" (Association of Socialist Pupils), an offshoot of the Young Communist League of Germany, in Berlin in 1931, and the Communist Party of Great Britain (CPGB) in 1936. He was a member of the Communist Party Historians Group from 1946 until its demise and subsequently president of its successor, the Socialist History Society until his death. The Soviet invasion of Hungary in 1956 led thousands of its members to leave the British Communist Party – but Hobsbawm, unique among his colleagues, remained in the party, but was distrusted by its leadership and ceased political work by the end of the 1950s. Hobsbawm maintained some ties to former colleagues such as E. P. Thompson and John Saville who had left the CPGB at this time and became leading lights of the New Left in Britain, occasionally contributing to New Left publications but also providing intelligence reports on the dissidents to CPGB headquarters. He later described the New Left as "a half-remembered footnote". He signed a historians' letter of protest against the Soviet invasion of Hungary and was strongly in favour of the Prague Spring.