Gerard was educated at Winchester College; at New College, Oxford; and at St Bartholomew’s Hospital - entering as a student in 1911, he obtained the diplomas M.R.C.S., L.R.C.P. and qualified M.B., B.Ch. in 1914. During the second Balkan War he served in Bulgaria with the British Rad Cross Unit. On 31st July 1914 he gained a regular army commission in the R.A.M.C. at the rank of lieutenant and was promoted to the rank of captain on 30th March 1915. He entered the war in France in December 1914 and served as medical officer of the 1st Bn. Argyll and Sutherland Highlanders. He was wounded near Ypres in March 1915 and was invalided home. In 1916, after he recovered, he returned to France to join the 33rd Field Ambulance, but was later transferred at his own request to become medical officer to the 9th Bn. Lancashire Fusiliers. He was killed while attending the wounded between the lines at Mouquet Farm. Gerard was the son of Dr Prideaux George Selby and Elizabeth Mary Alice Selby of Brusons, Teynham, Kent.