John received his medical education at St Mary’s Hospital, Paddington, London, qualifying M.R.C.S., L.R.C.P. in 1893. He joined the Medical Services, at the rank of Surgeon Lieutenant on 29th July 1895, then received promotion to Captain on 29th July 1898. In 1900 he began active service in South Africa, being invalided home to Plymouth in 1901. For his service there he received the Queen’s South African Medal with 4 clasps. On 29th January 1907 he gained promotion to Major. At the outbreak of war, John was stationed in Warrington. He was posted to be the Commanding Officer of the 5th Cavalry Field Ambulance, entering the war in France with the unit on 18th August 1914. On 1st March 1915 he gained promotion to Lieutenant Colonel, then on 3rd July 1916 he was granted the rank of temporary Colonel whilst acting as Assistant Director of Medical Services to the 4th Division.