Lennox Eales was born in Plumstead, South Africa. His father William Clarence Eales was a university lecturer and his mother Hilda Mary, née Webber, was the daughter of a businessman. His early education was at Rondebosch Boys High School and he went on to the University of Cape Town to study medicine. He graduated with first class honours, pursuing his clinical studies at Groote Schuur Hospital, and was awarded the university gold medal and the university council scholarship. After completing his internship at the Groote Schuur, where he was house physician to J F Brock, he enlisted in the South African Medical Corps and saw active service for five years in the Middle East, North Africa and Italy, rising to the rank of captain.

After the war he was awarded a Nuffield Dominion medical fellowship which enabled him to come to Britain and take up a post as postgraduate research assistant at the Royal Postgraduate Medical School, Hammersmith. He obtained his membership of the College in 1947 and was appointed clinical and research assistant to Clifford Wilson at the London Hospital.

In 1949 he returned to Cape Town to take up a post as first assistant to J F Brock and in 1952 was appointed lecturer in the department of medicine at the University of Cape Town, and specialist physician at the Groote Schuur Hospital. He became deputy director of the University/CSIR clinical nutrition unit, which was headed by Brock, and in 1956 was awarded a Rockefeller fellowship which allowed him to spend a year at Stanford University, USA, where he continued his research into renal disease. On his return in 1957 he was promoted to associate professor and appointed director of the newly created UCT/CSIR renal metabolic research group. He was elected to the fellowship of the College in 1960 and in 1964 was appointed professor of clinical medicine at the University of Cape Town, a post he occupied for the next 19 years. He became director of the UCT/MRC porphyria and renal metabolic research group in 1967, which later became the UCT/MRC porphyria research unit.

Len Eales excelled in every sphere of academic medicine. He set great store on clear, logical thinking in clinical practice and his incisive approach to difficult diagnostic problems resulted in his opinion being sought by colleagues practising all over South Africa. His knowledge of his field extended well beyond that of the ordinary clinician; he revelled in complex chemistry, biochemistry and physiology. For him metabolic pathways, water, electrolyte and acid/base balance were a source of delight to be shared with his colleagues and students. This enthusiasm, logical approach and ability to synthesize complex information, made him a great teacher.

Eales’ research in the field of porphyria gained him international recognition. He published his first paper in this field as a fifth year medical student and he went on to become a world authority on the clinical and laboratory features of variegate porphyria in general and of the acute porphyria attack. The first and second international conferences on porphyria, organized by Eales and held in Cape Town in 1963 and 1971, attracted the world’s most distinguished researchers in this field. Len Eales published more than 160 papers and edited or contributed to many books. Most important of all was his ability to stimulate and train a large number of young biochemists and physicians, many of whom are still working as nephrologists or in the field of porphyria.

Eales received numerous awards in recognition of his work, including the silver medal of the Medical Research Council of South Africa. He was elected a life fellow of the University of Cape Town in 1963 and a Fellow of the Royal Society of South Africa in 1979. In 1985 his friends and students honoured him with a festschrift on porphyria, published as a book by Clinics in Dermatology.

Len Eales’ health began to fail in the late 1960s. Typically, he bore this with great fortitude. He seldom complained, even when a bad fall resulted in a fractured femur he hid his pain and entertained those visiting him in hospital with ‘lectures’ on porphyria, the history of the second world war, or the cultivation of proteas and ericas. Sadly, his illness prevented him from enjoying his hobbies after his retirement in 1983, but he remained an avid reader; the history of the second world war and ancient history being his favoured topics.

Eales loved nature. As a young boy he enjoyed fishing in Kalk Bay, and as a young man he excavated historic pre-bushman caves in the mountains above the Bay. His later hobbies included developing a protea plantation at the family home in Pringle Bay where he collected and propagated rare and endangered species of this national flower.

Len Eales married Irene Gee in 1946. They had three children: Peter Lennox, Patricia Anne and Margaret Jane. Irene’s quiet but intense devotion and care for Len served as an inspiration for all who knew them.

Lennox Eales made an indelible impression on medicine in South Africa, his influence being felt not only in Cape Town but in porphyria laboratories throughout the world.