John received his medical education at Guys Hospital, London, qualifying M.R.C.S., L.R.C.P. in 1899. During his medical career he became a specialist in Ophthalmology. On
17th November 1899 he gained a commission within the Medical Services at the rank of Lieutenant, then saw active service in South Africa from 1899 to 1902, receiving the Queen’s South African Medal & 3 clasps and the King’s South African Medal & 2 clasps. On 17th November 1902 he gained promotion to the rank of Captain, then was stationed in India from 1902 to 1904 and again from 1909 to 1914, during which time he gained promotion to the rank of Major on 17th November 1911.
After war was declared John assembled at Aldershot to form ‘unit No 1’, Hospital Ships (‘St David’), becoming the Commanding Officer. The ship first sailed from Southampton to Havre on 24th August 1914. On 16th August 1915 he began to serve under the rank of temporary Lieutenant Colonel. He became the Commanding Officer of the 67th Field Ambulance, which arrived in France on 7th September 1915, then transferred to Salonika the first week in November. In 1916 he took over as Commanding Officer of No 31 Casualty Clearing Station, and remained with the unit until 1918 when he left Salonika. During this time, on 26th December 1917, he gained the rank of Lieutenant Colonel.
After the war John returned to India, where he served until he retired, with pay, on 17th November 1923. He ceased to be on the Roll of Officers on 28th December 1926.