In 1831 a terrifying new epidemic arrived in London, bringing with it fear and panic—and a sense of urgency about the city's sanitation problems. In the 1700s, Great Britain began transforming into an industrialised nation. By the 1800s, London was the largest city in the world as a result of the social changes brought about by industrialisation, such as mass migration from the countryside to the town. But London was a city overwhelmed by the waste products of its ever-growing population, the majority of whom lived in the squalor of overcrowded slums. Human waste piled up in courtyards and overflowed from basement cesspits into the gutters and waterways. Wellcome Collection (CC BY) Image source for Illustration of London slum with subtitle 'A court for King Cholera' In such conditions diseases were inevitable. Outbreaks of diseases such as typhoid and scarlet fever were common, but the arrival of cholera led to new investigation into sanitation and