[1] Graduating with a bachelor's degree from Imperial College London, Hartley worked for the North Eastern Railway and an asphalt manufacturer before joining the Royal Flying Corps during World War I.

Following the war he was rewarded with an appointment as Commander of the Order of the British Empire (CBE), a United States Medal of Freedom and £9000 cash.

After graduation he found employment with the North Eastern Railway in the office of their chief docks engineer at Hull and from 1912 to 1914 with asphalt makers Rose, Down and Thompson Limited.

He was responsible for the Air Board's development of George Constantinescu's interrupter gear which allowed a machine gun to be fired through the propeller blades of an aircraft without danger of damage.

[1] He became assistant manager of the supply department later the same year and from 1932 to 1934 he was seconded to the Iraq Petroleum Company, on his return being appointed chief engineer.

Here he developed, at the request of Air Chief Marshal Arthur Harris, the Fog Investigation and Dispersal Operation which was known as FIDO.

[9] The system supplied the allied armies with 1 million US gallons (3,800 m3) of fuel per day during the advance into Germany, and Hartley received £9000 after the war for his work on Pluto from the Royal Commission on Awards to Inventors.

[2] He retired from Anglo-Iranian (which would become British Petroleum in 1954) in 1951 and became an engineering consultant during which time he developed the Hartley hoister – a device which allowed the loading of oil tankers offshore.