David Byrne is Professor of Sociology and Social Policy at the School of Applied Social Sciences, University of Durham. His recent publications include Applying Social Science (Policy Press, 2011) and Social Exclusion (Routledge, 2008).Gillian Callaghan is Lecturer in Sociology at the University of Durham. Her research interests focus around the use of complex realism as a basis to develop the coherence of the relationship between theory, methods and empirical research. Her work has been published in journals such as Sociological Research Online and Critical Social Policy .