He is estimated to have a personal fortune of billions of pounds, derived from his family's Sainsbury supermarket chain. He was a supporter of the Social Democratic Party, and bankrolled it, but moved to Labour Party following the failure of the SDP to make much progress. He has donated millions of pounds to the Labour Party, and was associated with the Institute of Public Policy Research.
He was made a life peer in 1997, following Labour's election victory, and is now Parliamentary Under-Secretary of State for Science in the House of Lords.