Acknowledgement: We thank our co-applicants and collaborators in the grant application to the MRC for advice and for their permission to publish this editorial. All of them have seen and commented on the penultimate draft. The London and Edinburgh team involved in the grant application comprises Raj Bhopal, Gene Feder, Aziz Sheikh, Robin Prescott, Sarah Wild, Christopher Griffiths, Charles Wolfe, Pankaj Sharma, Patrick Gompertz, Khalid Darawil, Adrian Martineau, Anna Livingstone.