Ashby was a prominent figure in a small group who pioneered agricultural economics as a separate area of study. During the years he spent at Aberystwyth he had an opportunity to reveal his talent in this field; he gave strong leadership both within the college and in agricultural circles outside. The education of young country people was important to him, and as a member of the committee which awarded scholarships to the sons and daughters of rural workers he had an opportunity to do his best for them over the years. With his practical experience of farm life and work he endeavoured as a member of the Agricultural Wages Board from 1924 onwards to maintain and deepen the good relationship between farmers and farm-workers. He also worked tirelessly to promote agricultural co-operation and supported the activities of the Welsh Agricultural Organisation Society. He played a great part behind the scenes in forming agricultural marketing schemes, including establishing the Milk Marketing Board, which more than any other initiative was responsible for bringing the agriculture of the lowlands of Wales (and the whole of the United Kingdom for that matter) out of poverty from 1933 onwards.

He contributed numerous articles on his subject to many journals, and his book (with Ifor L. Evans, 1897-1952; see below) in 1943, The Agriculture of Wales and Monmouth, is a mine of information on agricultural history for the period 1867 to 1939. He received an honorary degree of M.A. from the Univ. of Wales in 1923 and M.A. by decree in 1946 from the University of Oxford; he was elected a fellow of Lincoln College, Oxford in 1947. He was a justice of the peace, and was appointed a C.B.E. in 1946. In 1922 he m. Rhoda Dean Bland and they had one son. He d. 9 Sept. 1953, in Radcliffe Infirmary, Oxford.