1. Department of Social Science, University College London, Institute of Education, London, United Kingdom
2. Division of Health Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
3. Cardiff School of Social Sciences, Cardiff University, Cardiff, United Kingdom
4. School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom
5. Department of Social and Environmental Health Research, London School of Hygiene and Tropical Medicine, London, United Kingdom