Colin Gill was a physicist whose early work on masers and parametric resonance inspired his research into the thermodynamics of spin-systems in solids, in particular the establishment of thermal equilibrium in paramagnetic crystals at low temperatures. This, and his later work on low-dimensional phenomena in solids, notably charge-density-waves, were highly regarded internationally.

Graduating with First-Class Honours in Physics from the University of Manchester in 1952, Colin remained there, as a student at Jodrell Bank, working under the supervision of Professor JG Davies on the orbits of meteors. He was awarded a PhD in 1956. Joining the Scientific Civil Service at the Royal Radar Establishment at Malvern in the same year, he rose to be a Senior Scientific Officer, before being appointed Lecturer in Physics at the University of Bristol in 1962. From then until his early retirement in 1988, he taught a wide range of undergraduate courses to mainly honours students and gave occasional lectures and seminars on his most recent research work, which was often closely related to that of other members of the Department, in theoretical physics and the electronic properties of solids. His quiet disposition was reflected in his preferred style of working, which was to be alone or with one or two members of his research group, many of whom became lifelong friends, having initially been attracted by the breadth of his knowledge. He was promoted to Reader in Physics in 1982. 

As an expression of his wider interests, Colin gave extramural courses on the application of physics to archaeology in 1966 and 1969 and was connected informally with the Area Archaeological Committee for Avon, Somerset and Gloucester, being its link with the Science Faculty at Bristol. He was for many years an active member of the Senior Common Room walking group, to which he contributed many local walks as well as leading from the front at a pace that few could match.

Colin was predeceased by his wife, Jennifer, whom he supported in her professional work as a restorer, and with whom he developed a productive garden on a one-time derelict plot of land by their home in Freeland Place. He died peacefully in a nursing home on 1 January 2023, at the age of 90. He is survived by his sister, Alison.