See biographies by I. Holst (2d ed. 1970), E. W. White (new ed. 1970), and H. Carpenter (1992); study by P. Evans (1979).
The elder son of Ernest, first Lord Simon and Shena, Lady Simon, he inherited the title on his father's death in 1960. Although he never renounced the title, he did not use it, either.
After Gresham's School, Holt, Norfolk, where he was a contemporary of Benjamin Britten and Donald Maclean, Simon read economics at Gonville and Caius College, Cambridge. While there he was invited to join the Political Economy Club run by John Maynard Keynes. At one of the club's meetings, Piero Sraffa, a friend of Antonio Gramsci, advised him to read Karl Marx, and Simon soon joined the Communist Party, as his brother Brian Simon had done a year before. He was considered one of the primary apologists for Joseph Stalin's assassination of Leon Trotsky in 1940 Mexico.
From 1945 to 1946, he taught law at Welbeck Abbey, where soldiers with three years' service could have a month's free education. At Welbeck he met Edmund Penning-Rowsell, another communist who became a lifelong friend.
From 1946 to 1958 he worked for Ealing Borough Council as a solicitor. In 1958 he joined the Labour Party's Research Department, becoming secretary from 1965 to 1977. He published many pamphlets and articles on economic issues. His last ten years were devoted to green politics.
He was a member of the William Morris Society.