John Lloyd joined what was then the Computing Laboratory as a postgraduate student in 1967, after obtaining a degree in Mathematics from the University of Manchester. He obtained a PhD in 1972. He became a Research Officer in the Laboratory in 1970, and was promoted to a Lectureship in 1973 and to a Senior Lectureship in 1994. He became Head of the Department of Computing Science in 1997, and was Head of the School of Computing Science from its establishment in 2002 until 2006. He was Head of the School of Natural Sciences (now the School of Chemistry) from 2006 until his retirement in 2008.
John's research interests, originally in numerical analysis, subsequently extended to cover aspects of computer graphics and of parallel computation, particularly for numerical and graphics problems. He has taught a wide range of courses, has acted as external examiner for degree programmes at a nubmer of universities and is currently external examiner for undergraduate degree programmes at De Montfort University, for postgraduate programmes at Northumbria University, and for overseas programmes of Staffodshire University delivered in conjunction with APIIT/UCTI, Kuala Lumpur, Malaysia. He is a member of the Academic Accreditation Committee of the British Computer Society and a former Secretary of the executive committee of the Council of Professors and Heads of Computing, the UK subject body for Computing. He has held visiting appointments at Northwestern University (1974) and at the University of Delaware (1985).