I started my public health training at a time when only doctors could do so. I had been working as a surgeon for several years, and it was quite a change. Very early in my transition, I became aware, of course, that medicine, and the medical model that I had been taught, explained only part of the public's health. Doctors and other health professionals have an important part to play in influencing the broader determinants of health and the system in which they work. But so, too, do many others.

When I became Chief Medical Officer for England, I strongly supported the notion that public health should not be the preserve of doctors – or, indeed, of any other single profession. Health is a complex interplay of many factors. The public's health is best improved by drawing on many different areas of expertise; therefore, public health needs to be multidisciplinary.

The public health workforce in England has shifted enormously in this direction over the last 15 years. The authors have done important work in studying and documenting this. Their findings make it clear that achieving this shift has not been easy. I hope that this book can serve as a reminder of this – so that what has been achieved can be built on further, and does not get lost.