James Cornford was born in London on 25 January 1935, the son of (Rupert) John Cornford and Rachel Peters. He was educated at Dartington Hall School; King's College School; Winchester College; and Trinity College, Cambridge. He married Amanda Goodfellow, in 1960, with whom he had one son and three daughters.

He undertook postgraduate work at Trinity College, Cambridge; the University of California, Berkeley; and the University of Chicago, 1958-64. He was a Lecturer in Politics, 1964-8, and Professor, 1968-76, at Edinburgh University. He was also a Visiting Fellow at All Souls College, Oxford, 1975-6.

In 1976, he took up the post of Director of the Outer Circle Policy Unit established by the Joseph Rowntree Foundation. He went on to become Director of the Nuffield Foundation, 1980-8; Director of the Institute for Public Policy Research, 1989-94; and Director of the Paul Hamlyn Foundation, 1994-7. He briefly served as an adviser to the Chancellor of the Duchy of Lancaster, David Clark, 1997-8.

He was also Chairman of the Campaign for Freedom of Information, 1984-97; Literary Editor and Chairman of The Political Quarterly, 1976-99; Chairman of the Southern African Advanced Education Project, 1990-9; Director and Chairman of Job Ownership Ltd, 1979-2002; Deputy Director and Chair of Trustees of the School for Social Entrepreneurs, from 2000; and Trustee and Chairman of the Dartington Hall Trust, 1998-2008.

He died on 26 September 2011.