Rotherham attended Herbert Strutt School in Belper. He graduated from University College in London in 1934 with first-class honors in physics.
In 1935, Leonard received a Master of Science degree for studies on the viscosity of liquids, supervised by Edward N. da C. Andrade. In 1958, Rotherham was awarded the Doctor of Science degree by the University College in London.
Leonard Rotherham started his career as a principal physicist who was in charge of the physics program at the Brown-Firth Research Laboratories in Sheffield, where he worked from 1935 to 1946. In 1946, Rotherham was appointed a head of the materials division at the Royal Aircraft Establishment in Farnborough. He led an outstanding team of scientists, whose work was both basic and applied, elucidating mechanisms of fatigue failure, an effort that was vitally important in materials selection and airframe design. Rotherham also considered possible roles for ceramics in jet engines. He was appointed director of Research and Development of the UK Atomic Energy Authority’s industrial group in 1950.
In 1958, Rotherham became a member for research in the newly formed Central Electricity Generating Board. Having additional control of several regional laboratories, Leonard led efforts of several thousand research workers whose output was commensurately large.
Then in 1969, Leonard was appointed vice chancellor of the University of Bath, where he worked until his retirement in 1976. During this time, Rotherham reorganized the administrative structure, appointed new high-quality staff, and set up the research base, particularly on the applied side. Following his retirement he became a governor of Imperial College in London and a director of Chemring Group.
Leonard was a council member of the Royal Society, 1965-1966 and Royal Academy of Engineering, 1976, Institution of Metallurgists (president, 1964), Institute of Metals (president, 1965).
Rotherhham was a quiet and reserved person, but highly determined. He did not tolerate fools gladly and could be abrupt in manner.
Leonard Rotherham married Nora M. Thompson in 1937 and they had a son and two daughters.