In the United Kingdom he was a pioneer in the application of modern methods for the measurement of bilirubin and other breakdown products of haemoglobin. This work contributed greatly to the introduction of practical procedures that could be used in hospital laboratories to help sort out the clinical problems of differentiating the causes of jaundice.
Collaboration with Albert Neuberger, working on the metabolism of porphyrin and its rare inherited disorders, the porphyrias (from which George III is believed to have suffered), stemmed from his studies of bile pigments in human disease. His team, using modern techniques, added significantly to the ability of the laboratory to identify the varieties of the porphyrias, putting the management of these cases on a more rational basis.
He introduced a number of practical chemical procedures for the investigation of diseases of the adrenal cortex which were ahead of their time but were of limited value and were superceded without coming into general use, although they contributed at the time to a greater understanding of these rare disorders.
Trained as a chemist at Imperial College, London, Gray moved on to physiology at University College London with a Bayliss-Starling Scholarship in Physiology and Biochemistry in 1932. This was followed in 1935 by a demonstratorship in biochemistry and then a lecturer post in physiology at UCL, which provided him with a salary, although meagre, enabling him to study medicine at the same time as continuing his work on bile pigments. He completed his qualifications in medicine in 1937.
The following year his research was of sufficient distinction for him to be invited to follow R.A. McCance as Biochemist at King's College Hospital Medical School in London. During the Second World War Gray saw service in charge of the Sector 9 Biochemical Laboratory in the Emergency Health Service. In 1948, he was given a personal chair in Chemical Pathology in London University, which he held at King's College Hospital, where he was the consultant chemical pathologist until he retired in 1976.
During those years, he built a strong research team which gradually established an international reputation in the many fields of his interest; he obtained some of his funding from major industrial drug companies - rather an innovation at the time. He was very friendly with his overseas research colleagues, so that his department, though often modest in resource compared with theirs, was a favourite place for sabbatical research.
During the years he was in charge of chemical pathology at King's College Hospital, there were great changes in the provision of laboratory services which grew to provide a wide range of investigative tools to help elucidate clinical problems in diagnosis and in the management of patients. Many of the repetitive analyses, previously performed by hand, were transferred to automated machines, allowing the investigation of individual patients on a scale that could not have been imagined at the time that he was appointed.
Finally, he saw the introduction into laboratory practice of computers that slowly but surely enabled the more effective use of such machines. He saw clearly that such advances allowed his skilled technical and scientific staff to spend more time undertaking manually the more complex analytical procedures that, though needed less frequently, were the sharp end of a hospital clinical laboratory's work. Many of these methods found their way from the research benches of the laboratory to the routine side of the department.
Charles Gray was a very reserved, though determined, man who did not easily make friends with his clinical colleagues. Nevertheless, he was widely respected for his firmly-held views on the importance of the scientific basis of medicine, and for the scientific reputation of his department that, at a time when resources for research were difficult to obtain, added lustre to the medical school.
He was a very conscientious head of department who liked to maintain close contacts with his staff. In more spacious times it was his custom to walk round the entire department first thing in the morning talking to every individual, from the senior to the most junior, asking how his or her work was progressing, giving advice and encouragement as he went.
He was a clear thinker and he wrote well, so that he was in considerable demand in later years for committee work and editorial responsibilities. He was for a period a member of the Clinical Research Board of the Medical Research Council; chairman of the research committee of the Arthritis and Rheumatism Council: member of the council of the Royal College of Pathologists. His editorial duties included the chair of the Committee of Management of the Journal of Endocrinology, and membership of the Editorial Board of the Biochemical Journal. He was for a time Secretary of the Society of Endocrinology, and in 1969 was elected President of the Association of Clinical Biochemists.
He wrote numerous scientific articles with his research associates, and a number of books which were standard texts in their time. Among his best- known books are an encyclopaedic work, Hormones in Blood (1961), and a small early work, The Bile Pigments (1953). A handbook of chemical pathology, Clinical Chemical Pathology (1953), for medical students that was also widely used as a primer for trainees in his field was very popular; it saw a number of editions and was translated into several languages.
In 1976, the year he retired, he was appointed Emeritus Professor of Chemical Pathology in the University of London. Needing to remain intellectually active, he continued with editions of two of his books and readily accepted an invitation to be the acting head of the Chemical Pathology Department at the Hospital for Sick Children, in Great Ormond Street, when Dame Barbara Clayton left to take up her chair in Southampton. He spent several happy years continuing his porphyrin studies and working on further editions of his books as a visiting professor at the Medical Research Council Clinical Research Centre based at Northwick Park Hospital.
Charles Horace Gray, biochemist: born Erith, Kent 30 June 1911; Consultant, King's College Hospital District 1938-76, Consulting Chemical Pathologist 1976-81; Professor of Chemical Pathology, London University 1948-76 (Emeritus); Honorary Consultant, Miles Laboratories Ltd 1953-76; Visiting Professor, Division of Clinical Chemistry, MRC Clinical Research Centre, Harrow 1976- 83; married 1938 Jessie Widdup (two sons); died Leatherhead, Surrey 15 August 1997.