Health inequalities seem both pervasive and durable. They exist in every country for which we have data, and they have been largely stable in recent years. The degree to which health inequalities are in fact durable over the long run is, however, unclear. We use deep learning and optical character recognition to combine, for the first time, individual level data for almost every person in England and Wales that died between 1860 and 1990 with data on wealth at death taken from probate records. Together, this newly constructed dataset provides the most detailed analysis of health inequalities over the long run ever to be conducted. We show that inequalities in life expectancy between the rich and poor decreased dramatically in the UK between 1860 and 1990, with particularly large reductions since 1940. We provide the most granular picture currently available on both when, and among which parts of the wealth distribution these changes in life expectancy occurred. These results touch on important debates among various academic disciplines (demography, economic history, and medicine) concerning the inequalities underlying the demographic transition, the ‘fundamental causes’ of health inequalities, and the impact of industrialisation on society.