Sally Mary Caroline Belfrage was born in Hollywood, California, on 4 October 1936. Her parents, Cedric Belfrage and Molly Castle, later moved to New York where Sally studied at the Bronx High School of Science and Hunter College, before her parents were deported to London as alleged Communists. After her return to England, Sally Belfrage matriculated at the London School of Economics, and after graduation she attended 6th World Festival of Youth and Students in Moscow, went to Communist China and worked for the Foreign Languages Publishing House, Moscow, in 1957.