Luke's first official appointment was as private secretary in Sierra Leone in 1908. He became aide-de-camp the following year, and briefly acted as Colonial Secretary for a few months. In 1911 he moved to Barbados to become private secretary to the Governor.[3] He subsequently served as private secretary to the High Commissioner of Cyprus (1911–1912) and as commissioner of Famagusta (1918–1920). From 1909 to 1911 he was also a second lieutenant in the London Yeomanry.
From 1924 to 1928 Luke held the post of Colonial Secretary of Sierra Leone. He was subsequently appointed to be the acting High Commissioner to the Government of Palestine. He assumed this position on 19 July 1928 and held it until 6 December 1928.
On his retirement from the Colonial Service in 1943, Luke served for three years as chief representative of the British Council in the Caribbean. He died in Cyprus, where he often spent the winter, on 11 May 1969.
In 1918 Luke married Joyce Evelyn Fremlin, the daughter of Henry James Leigh Fremlin and his wife, Maud Evelyn Deane (divorced 1949). They had two sons, Peter Ambrose Cyprian Luke, born in 1919, and Michael Charles Deane Luke, born in 1925.[8]
The Fringe of the East. Journey through Past and Present Provinces of Turkey, (Macmillan & Co), 1913 (First published under the name Harry Charles Lukach)
The City of the Dancing Dervishes, 1914
Cypriote Shrines, (Faith Press), 1920
The Handbook of Cyprus (London), 1920 (together with D.J. Jardine)
Report of the commission appointed by the government of Palestine to inquire into the affairs of the orthodox patriarchate of Jerusalem, 1921 (together with Anton Bertram)
The handbook of Palestine, 1922 (together with Edward Keith Roach)
Anatolica, (London), 1924
Mosul and its minorities, 1925
Prophets, Priests and Patriarchs: sketches of the sects of Palestine and Syria, 1927