The study was funded by the Department of Health Policy Research Programme (http://prp.dh.gov.uk/) (Policy Research Unit in Behaviour and Health [PR-UN-0409-10109]). ASA and MRM are members of the UK Centre for Tobacco and Alcohol Studies, a UKCRC Public Health Research: Centre of Excellence. Funding from British Heart Foundation, Cancer Research UK, Economic and Social Research Council, Medical Research Council, and the National Institute for Health Research, under the auspices of the UK Clinical Research Collaboration, is gratefully acknowledged. None of the funders had a role in the study design, data collection, analysis, interpretation, or decision to submit for publication. The research was conducted independently of the funders, and the views expressed in this paper are those of the authors and not necessarily those of the funders.