Nicholls attended the Whitechapel Foundation School. He entered St Bartholomew's Hospital Medical College on 25 October 1869Button, Clare, Archivist, Barts & The London School of Medicine and Dentistry; March 2020 from where, in 1870, he was awarded, in the examination of practical anatomy at St Bartholomew's Hospital, a certificate, examiner's prize, and the Proctorship. The following year he delivered a lecture at school on "The digestive system", concluding a course on physiology. He graduated in medicine (MB and CM) at the University of Aberdeen in 1873, and gained his MD degree from St Bartholomew's Hospital in 1875. Almost immediately he emigrated to Dominica, to serve as Assistant Medical Officer to Dr John Imray who had been there since 1832.
