John received his medical training at Charing Cross Hospital, qualifying L.S.A. in 1879 and M.R.C.S. in 1880. On 30th July 1881 he took up a commission at the rank of Surgeon Captain within the Medical Services, then gained promotion to Surgeon Major on 30th July 1893. From 1899 to 1902 he was serving in South Africa. On 30th July 1901 he gained promotion to the rank of Lieutenant Colonel, then was promoted again on 8th August 1910 to Colonel. At the outbreak of war he was appointed as Assistant Director of Medical Services (3rd Army) in the Central Force for defensive and offensive operations in the event of an invasion. He was promoted to Surgeon-General on the 1st March 1915. In 1917 he was appointed Companion of the Order of the Bath, and Knight of Grace Oder of St John of Jerusalem 1917.