Ernest Thomas Garton Sherwood attended the high school of the South African College, Cape Town, from 1898 and passed the matriculation examination of the University of the Cape of Good Hope in 1900. He was awarded a University Exhibition at matriculation and continued his studies at the South African College that same year. In 1902 he was awarded the BA degree with honours in mathematics and natural science by the University of the Cape of Good Hope, having obtained the highest marks of all candidates who completed the degree that year. He also received the George Grey Memorial Scholarship.
Sherwood appears to have remained at the South African College for some time after graduating, but then proceeded to England where he continued his studies at King's College, University of Cambridge. He was awarded the BA degree (later upgraded to an MA) in 1905. After returning to the Cape Colony he joined the civil service and was appointed as a clerical assistant in Cape Town in 1906. In or before 1911 he was appointed as lecturer in physics at the Transvaal University College in Pretoria, under Professor P.G. Gundry*. He held this position to about 1916, when he became the first lecturer in applied mathematics at the college. He appears to have been promoted to the rank of professor later.
Sherwood was married to Emily Louise, born Minhinnick, with whom he had two sons (he was the second of her three husbands).