1. Statistics Consultant to NHS Cancer Screening Programmes, Fulwood House, Old Fulwood Road, Sheffield S10 3TH, UK
2. HPV and Cervical Cancer Group, Centre for Cancer Prevention, Wolfson Institute of Preventive Medicine, Queen Mary University of London, EC1M 6BQ
3. NHS Cancer Screening Programmes, Fulwood House, Old Fulwood Road, Sheffield S10 3TH, UK
4. Emeritus Professor of Public Health, Unit of Health Care Epidemiology, University of Oxford, UK