Born 21 February 1872 at Barnet, Hertfordshire, the second child and second son of Thomas Douglas, civil engineer, and Isabella McLaren his wife. He was educated at Dulwich College and St Bartholomew's Hospital, where he served as house surgeon, resident midwifery assistant, and demonstrator of anatomy. He took the London MB with honours in medicine, obstetric medicine, and forensic medicine, in 1896 and the Conjoint qualification in the same year. Douglas entered the service of the Burma Railways and ultimately became their chief medical officer at Rangoon. In the course of his service he took several higher degrees, as shown in the list at the head of this memoir. He never married. After his retirement from work in the East he lived with his sister at 60 Ashley Gardens, London, SW1, where he died on 26 January 1950, aged 77. Douglas left £500 to St Bartholomew's Hospital for the research work of the pathological department, £500 each to the Imperial Cancer Research Fund and the Seamen's Hospital Society, and £1,000 each to the Warspite Training Ship and the Church of England Waifs and Strays Society.