University of Exeter, University of Exeter - Health Economics Group, University of Oxford, Office for Health Improvement and Disparities, London School of Hygiene & Tropical Medicine - Department of Public Health, Environments and Society, London School of Hygiene & Tropical Medicine, University of Cambridge - School of Clinical Medicine, University of Cambridge, University College London - Great Ormond Street Institute of Child Health, University of Cambridge, University of Cambridge - MRC Epidemiology Unit, London School of Hygiene & Tropical Medicine, University of Hertfordshire, University of Cambridge - MRC Epidemiology Unit, University of Cambridge - MRC Epidemiology Unit, University of Cambridge and University of Exeter - Faculty of Health and Life Sciences