The recent emphasis on HSS has arisen primarily at the international level, within intergovernmental organisations (IGOs) and in the field of global health. Greater emphasis is being placed on the idea that some targeted health programmes fail because they are designed and implemented without adequately considering the characteristics of the broader health system. This is important because services within a health care system are interdependent: “vertical” programmes that address one disease or health issue require sufficiently strong “horizontal” support and coordination across various health service sectors. This relationship always has been important, but the challenges of the Ebola crises in particular in the past few years have made that clearer. Although HSS discussions often focus on low- and middle-income countries, many of the ideas apply equally to countries such as the UK, specifically in planning for the future.