Having qualified in medicine, I have spent my career evaluating health care and developing ways in which we can assess the quality of care people receive and ways of improving it. For the past 30 years I have worked at the London School of Hygiene & Tropical Medicine, a post-graduate school with students from throughout the world. In recent years I have spent increasing amounts of time advising the NHS and government agencies as to how care might be improved. While achieving change is always difficult, it is essential for policymakers to understand the historical roots of how and why things are the way they are. My book, Walking London's Medical History, attempts to raise awareness and understanding of our current health services, the first step to the changes that are necessary.