Born in Leytonstone in Essex, he was educated at the City of London School and the Royal College of Science, where he graduated with a Bachelor of Science. He was then demonstrator at the Imperial College from 1926 to 1929. In 1929, he received a Harkness Fellowship to the University of Chicago. Ashby was a lecturer at Imperial College from 1931–35, and at the University of Bristol from 1935–38.
Ashby married Elizabeth Helen Margaret Farries, whom he met while they were working together on incineration techniques for measuring carbon in tissue. They had two children, Michael and Peter.
In 1938, Ashby became professor of botany at the University of Sydney, a post he held until 1946. Between 1944 and 1945, he was Scientific Counsellor to Moscow. From 1947 to 1950, he held the Harrison Chair of Botany at the University of Manchester. According to Burges and Eden"His enthusiasm and flair for botany made Manchester one of the leading botanical schools in the United Kingdom".
From 1950-59 he was president and vice-chancellor of Queen's University, Belfast. For the University of Cambridge, he was Master of Clare College, Cambridge from 1959–75, and vice-chancellor from 1967-69. From 1968-74 he was Chairman of the Governors at Culford School; and between 1970–73, he was chair of the Royal Commission on Environmental Pollution. Ashby was knighted in 1956, and was created a life peer as Baron Ashby, of Brandon in the County of Suffolk on 6 July 1973.
Ashby was secretary of the Society for Experimental Biology from 1935 to 1938 and president of the British Association for the Advancement of Science from 1962 to 1963. He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1961.
In 1968, he received the Centenary Medal of the Royal Society of Tasmania and in 1973, he became president and chancellor of the Queen's University, Belfast. He was adviser to the British National Fruit Traders Association and a Fellow of the Royal Society (FRS). He was awarded an Honorary Degree (Doctor of Science) by the University of Bath in 1966.
- Heslop-Harrison, J. (1995). "Eric Ashby, Baron Ashby, of Brandon, Suffolk, Kt. 24 August 1904-22 October 1992". Biographical Memoirs of Fellows of the Royal Society. 41: 2–18. doi:10.1098/rsbm.1995.0001.
- Profile Archived 25 September 2006 at the Wayback Machine, royalsoced.org.uk; accessed 18 April 2016.
- "The Oxford Dictionary of National Biography". 2004. doi:10.1093/ref:odnb/50791. Cite journal requires
- "No. 40706". The London Gazette. 10 February 1956. p. 825.
- "No. 46826". The London Gazette. 12 July 1973. p. 8057.
- Leake, Chauncey D. (8 November 1963). "Meeting: British Association for the Advancement of Science". Science. 142 (3593): 688–689. doi:10.1126/science.142.3593.688. PMC 2524738. His presidential address to the BA was entitled Investment in man.
- "Book of Members, 1780-2010: Chapter A" (PDF). American Academy of Arts and Sciences. Retrieved 25 April 2011.
- Profile, bath.ac.uk; accessed 18 April 2016.
Sir David Lindsay Keir
| President and Vice-Chancellor of Queen's University Belfast
Dr Michael Grant
| Master of Clare College, Cambridge
Robert Charles Oliver Matthews
| Vice-Chancellor of the University of Cambridge
Sir Tyrone Guthrie
| Chancellor of Queen's University Belfast
Sir Rowland Wright