Tankie was a pejorative term referring to members of the Communist Party of Great Britain who followed the Kremlin line, agreeing with the crushing of revolts in Hungary and later Czechoslovakia by Soviet tanks. Detractors accused the Soviet Union of social-imperialism.
The term originated from 1956, when the CPGB lost a lot of members, who left in protest at the Soviet invasion of Hungary. Those who left either became part of the anti-revisionist movements, embraced Trotskyism, or left Communism altogether.