DAVID BUTLER, a Fellow of Nuffield College, Oxford, has been associated with the Nuffield election studies since 1945 and has been the author or co-author of each one since 1951. He is well known for his election commentaries on television and radio, and he has written widely on British, American and Australian politics. DENNIS KAVANAGH is Professor of Politics at the University of Liverpool, having previously been Professor of Politics at the University of Nottingham and Senior Lecturer in Government at Manchester University. His works include Political Science and Political Behaviour, Thatcherism and British Politics, British Politics: Continuities and Change, Politics and Personalities, and The Politics of the Labour Party. He has been the co-author of the Nuffield election studies from 1974 onwards.