David Byrne is Emeritus Professor of Sociology and Applied Social Science at Durham University, UK. His research interests include complexity theory, post-industrial social structures, urban systems, taxation policy, the privatization of welfare systems, quantitative methods, and case-based methods. He is the author of Applying Social Science: The Role of Social Research in Politics, Policy and Practice (Policy Press, 2011), Class after Industry (Palgrave Macmillan, 2018) and Inequality in a Context of Climate Crisis after COVID: A Complex Realist Approach (Routledge, 2021) and co-author of Complexity Theory and the Social Sciences: The State of the Art (First Edition, Routledge, 2013) and Paying for the Welfare State in the 21st Century (Policy Press, 2017).

Gillian Callaghan is a teacher of social theory and qualitative methods and an experienced evaluator of social and health interventions. Her research interests include complexity theory, deindustrialization and post-industrial social structure, class, social capital and community, and issues of power, participation, and governance. She is the author of numerous journal articles and co-author of Complexity Theory and the Social Sciences: The State of the Art (First Edition, Routledge, 2013).