As a boy, Gurney was educated at Winchester College. During World War I, he joined the British Army, and served with the King's Royal Rifle Corps from 1917 to 1920. After a brief spell at University College Oxford, he joined the British Colonial Service in 1921, and was posted to Kenya as an assistant district commissioner. In 1935, after fourteen years in Kenya, he was appointed Assistant Colonial Secretary to Jamaica. After a brief stint working at the Colonial Office in London, Gurney served as Chief Secretary to the Conference of East Africa Governors from 1938 to 1944, and Colonial Secretary in the Gold Coast from 1944 to 1946. In 1946, he was appointed Chief Secretary to Palestine, serving until the end of British rule there in 1948. While serving in Palestine, Gurney was instrumental in crafting British policy during the Jewish insurgency in Palestine.