 Upon entering the customs service, Hart began drawing up a series of regulations for the operation of the customs house in Canton.For two years, from 1859 to 1861, Hart worked hard in Canton, but never fell ill in the hot and damp climate.In 1861, facing the threat of the Taiping Rebellion marching on Shanghai, Horatio Nelson Lay sought leave to return to Britain to nurse his injuries sustained during an anti-British riot in 1859.