[2] He then changed to modern history and graduated in 1912 with a first class honours Bachelor of Arts (BA) degree.
[3] In 1912, he was elected to a prize fellowship at All Souls College, Oxford, and spent time abroad learning foreign languages.
[2] Clark had been a member of the Officers' Training Corps attached to the University of Oxford during his studies.
[3] In 1930, he edited and provided a preface to the work Europe from 800 to 1789, the final and posthumous publication of historian H. W. C. Davis.
He became the inaugural Chichele Professor of Economic History at the University of Oxford in 1931 (with the accompanying Fellowship at All Souls), a post he held until 1943.
He stated that "knowledge of the past has come down through one or more human minds, has been processed by them, and therefore cannot consist of elemental and impersonal atoms which nothing can alter..."[8] Between the 1930s and 1960s, Clark was the editor overseeing the Oxford History of England series and wrote Volume X: The Later Stuarts, 1660–1714 (1934), which was the first of the series to be published.