During this period in Cambridge he made outstanding contributions to the so-called "New Field Theory'' proposed by Born and Infeld. He also wrote an incisive paper demolishing the then fashionable idea that light quanta might consist of pairs of neutrinos. Paul Dirac, then one of the most influential theoretical physicists, was so impressed (which was a very rare occurrence) that he spontaneously offered to communicate the work to The Royal Society. Maurice Pryce later remarked that this was the high-point of his scientific life.

In 1939 he was appointed to a Readership in Theoretical Physics at Liverpool University, and married Margarete (Gritli) Born. At the advent of war he joined the team working on radar at the Admiralty Signal Establishment, and 1944 transferred to the Joint Atomic Energy Project in Montreal. In 1945 he returned to his fellowship at Trinity College, Cambridge, and a university lectureship, but was soon invited to become Wykeham Professor of Physics at Oxford, a chair which had recently been earmarked for a theoretical physicist after the long tenure of Sir John Townsend. It was a bold appointment for someone aged only 32; he looked so much younger than his years that he was once famously challenged by the Proctors' men while drinking in the King's Arms, a favourite meeting place for Oxford physicists. He was mistaken for one of the undergraduates, who at that time were forbidden by the University authorities to enter public houses.

At Oxford he rapidly acquired a large group of research students, many returning from war service, several of whom were to become very distinguished in their fields. His interests and knowledge spread across many branches of physics, and students were put to work on widely ranging topics stretching from field theory, the nuclear shell model, liquid helium, to solid state physics. Maurice Pryce became most directly involved in interpreting the magnetic properties of atoms which were being studied in great detail through the paramagnetic resonance techniques by Brebis Bleaney and his colleagues in the Clarendon Laboratory. Almost half his published work relates to this area where he elucidated in detail the interaction between the magnetic electrons and the lattice (the crystal field), the effective lattice dynamics (the Jahn-Teller effect) and interaction with the nucleus (hyperfine structure). He also added considerably to the understanding of the magnetic properties of atoms in the actinide series, including the newly discovered transuranics. During his time in Oxford he took sabbatical leave to spend a year as Visiting Professor at Princeton. On his return he acted as the part-time head of the theoretical physics division at the nearby Atomic Energy Research Establishment at Harwell, where he replaced the previous head, Klaus Fuchs, who was arrested in 1950 and convicted on a charge of spying. In 1951 Maurice Pryce was elected a Fellow of the Royal Society.

In spite of the successful scientific enterprise which he was leading he became frustrated by the constraints of his position and in particular by the autocratic management of Lord Cherwell who, as head of the Clarendon Laboratory, controlled the budget and the appointments: this was before the creation of a separate department of theoretical physics. So in 1954 he accepted an invitation to succeed Nevill Mott as Henry Overton Wills Professor of Physics at the University of Bristol. With greater administrative duties as head of the department he had less time to develop his research group but he continued with the subjects that he had begun at Oxford. His first marriage had broken down, and he married Freda Kinsey in 1961. He then found a financially advantageous offer made by the University of Southern California very tempting, and he moved there in 1964 with the promise of resources to build up, essentially from scratch, a first class physics department. The reality turned out to be less attractive than he had hoped and he moved again to a chair at the University of British Columbia in Vancouver in 1968 where he was to remain until his death on 24 July 2003 at the age of 90.

During these later years Maurice Pryce had relatively few research students and close collaborators and published rather little. His main contributions were in the quite different field of astrophysics although others on molecular photoionisation and on the properties of the hydroxyl radical continued to display his versatility and his wide understanding of physics. This knowledge was greatly valued by his colleagues who would rely on a critical appraisal of their work and its interpretation. But he did not suffer fools gladly and was a harsh critic; in a seminar he could devastate the speaker and embarrass the audience with his acerbic comments.

He also continued his interest in atomic energy derived from his wartime work and was latterly a member of the Technical Advisory Committee to the Atomic Energy of Canada Limited with a particular interest on nuclear fuel waste management. Some of his last work related to the questions of the safety of deposit of radioactive materials in geological structures.

Maurice Pryce through much of his life was a keen walker and camper and, when he was younger, dinghy sailor. He was a competent pianist and liked to relax by playing classical music, mainly Bach and Mozart. He was a good cook, which stood him in good stead when entertaining friends and family after his second wife died in 1989. He inherited from his father a love and knowledge of gardening, which he passed on to all four of his children.

He always kept a boyish liking for silly games, from elaborate sand castles on the beach to noisy card games on the living room floor. Until ill health stopped him, he was a skilful Scrabble player. He created a family tradition, perhaps characteristic of his personal philosophy, of Collaborative Scrabble -- the main aim is, within the rules, to maximise the overall score rather than to beat the other players.

The mathematical gene has also passed on to his son John, well known in his field of mathematical software engineering; and to John's son Nathaniel, a professional software engineer.

The last four years of his life were spent in the University Hospital in Vancouver, incapacitated by osteoporosis-induced bone fracture and subsequent infection. During this period his mind was unaffected, and he bore immobility and frequent pain with patience, courage and a sense of humour. He remained in exemplary good spirits and was visited daily by a close friend of long standing, Eileen Goldberg, the widow of a South African lawyer who had been active in the fight against apartheid.

He is survived by his son John and three daughters Sylvia, Lois and Suki, all from his first marriage.

Roger Elliot

John Sanders