When I was 14 I worked in Newcastle as a medical apprentice. It was there that I encountered Cholera for the first time and learnt about the devastating effects of the disease. I think it was this experience – seeing how unwell Cholera made people that encouraged me to look closer at how the disease was spread. At the time many people (including leaders in the field like Florence Nightingale) believed that diseases were spread through bad air, but my observations in Newcastle didn’t seem to fit with that idea. By the time the Broad Street epidemic started in 1854 I was quite confident that dirty water was the culprit.