Frank Byrom was born in Wigan, the son of Thomas Henry Byrom FRIC FCS, chief analytical and research chemist of the Wigan Coal and Iron Companies, and lecturer at the Mining and Technical College. He came of an old Lancashire family which, in the 17th century, produced John Byrom, composer of the carol ‘Christians Awake’. From the Stationers’ Company’s school Frank entered the London Hospital medical college, where he had a distinguished student career, carrying off most of the undergraduate prizes. He was awarded honours with distinction in medicine in the London MB, and proceeded to hold a long sequence of house appointments at the London Hospital, including house physician to the medical professorial unit and resident accoucheur. From 1927 to 1930 he was medical first assistant to Leyton-Riddoch and during this period he acted as demonstrator in physiology, and carried out research on blood phosphorus in health and disease with HD Kay FRS.

This was followed by a Rockefeller research fellowship at the University of Chicago, where he became interested in electrolyte and water metabolism. He returned to the medical unit at the London as Beit memorial research fellow, and over the next three years published studies on fluid and electrolyte balance in myxoedema, diabetes and epilepsy. At this point he joined forces with Clifford Wilson, who had visited Goldblatt’s laboratory (USA) where experimental hypertension was produced in dogs by renal artery constriction. There were, at the London, no facilities for working with dogs, but an ample supply of Wistar rats. Wilson and Byrom devised the tail plethysmograph method for making repeated blood pressure measurements in the rat. This ingenious invention opened up a whole field of research, since the rat, in its hypertensive behaviour, was found to resemble man more closely than did any other experimental animal. Constriction of one renal artery by an adjustable silver clip led to severe hypertension, with the production of vascular and glomerular lesions in the opposite kidney closely resembling those occurring in malignant hypertension in man. These experiments established the role of high blood pressure, whatever its cause, in producing renal vascular damage. They led to a concept of a vicious circle in hypertensive renal disease, and provided a rationale for medical and surgical measures calculated to lower the blood pressure.

In 1940, Byrom was appointed director of the postgraduate pathological unit at Prince Henry Hospital, Sydney, and during the war years he assisted in the building of a plant for freeze-drying plasma. He maintained his interest in experimental hypertension, and by a brilliant technique of micro-surgery he succeeded in implanting acrylic windows in the rat’s skull through which the superficial cerebral arteries of the hypertensive animal could be studied and photographed. He showed (contrary to existing theory) that cerebral arteries and arterioles were capable of focal and diffuse vasoconstriction, and that ‘vascular crises’ (resembling hypertensive encephalopathy in man) were associated with cerebral oedema and arterial necrosis.

Byrom returned to England in 1957 and, with a personal grant from the MRC, made his third outstanding contribution, namely the study of the responses of the retinal arteries to hypertension. Working with Peter Daniel at the Maudsley Hospital, and later returning to the London, he devised a technique for photography and ciné-photography of the retina of the anaesthetised rat. The results confirmed and amplified his earlier findings, and formed the basis of his view that hypertensive vascular damage results from dilatations of muscular deficient zones in the arterial wall. The techniques, results and conclusions, were published in his monograph: The hypertensive vascular crisis, which (wrote TF Fox, his life-long friend) ‘is a model of scientific writing; it illustrates his clinical approach, logical thinking and lucid expression; he was as elegant on paper as in the laboratory’. In appreciation of his outstanding contribution to our understanding of high blood pressure Byrom was invited to give the Volhard lecture in 1976 (in his 74th year) to the International Society of Hypertension. At times working under great difficulties in terms of staff, finance and accommodation, Frank was greatly sustained (and even given technical help) by his wife, Kathleen, daughter of artist Percival Stanger Prichard, and by his gifted family. Of their five children (three boys and two girls), two qualified in medicine at the London, and one of these married Frank John Goodwin FRCP, renal physician to the London Hospital.

Byrom retired to Sandgate and built himself a laboratory dedicated to the restoration and repair of early English clocks, which he collected and displayed with great success and enthusiasm. At the bottom of his garden was the Channel where he and his wife bathed at all seasons.