Modern slavery takes many forms and has only in recent decades come to wide public and political consciousness. The Modern Slavery Act 2015 consolidated a number of relevant offences, and introduced a maximum penalty of life imprisonment. The numbers of victims known to the authorities, and of prosecutions, have considerably increased in recent years, but modern slavery persists, both in the UK and worldwide.

A number of different statistical approaches have been used in the fight against modern slavery and other hidden crimes. I will survey and explore some of these, and consider their role leading up to the Modern Slavery Act and in subsequent developments.

Overall I hope that the lecture will provide the opportunity to reflect more widely on what is the best appropriate statistical contribution to what is an important and disturbing aspect of public policy. In particular there are broader questions about presenting statistical evidence in an area where there is so much uncertainty. Should we follow George Box’s dictum that “all models are wrong, but some are useful”? There are some (imperfect) analogies with Florence Nightingale’s own work and campaign leading to the Public Health Act 1875, which saved the lives of millions.