John Howell Halliday (1899-1990), cardiologist, and Sir George Clifton (1901-1987), ear, nose and throat surgeon, were born on 17 September 1899 and 22 April 1901 at Cooma, New South Wales, eighth and ninth of thirteen children of Edward James Halliday, staff surveyor, and his wife Isabel Wild, née Howell, both born in New South Wales. Despite early fears that John would not survive to adulthood, he attended King’s College, Goulburn, and matriculated in 1916 with first-class honours in mathematics. He studied medicine at the University of Sydney (MB, Ch.M., 1923), residing at St Andrew’s College. After graduation he was a resident medical officer at Royal Prince Alfred Hospital (1923-24), and at the Coast Hospital (1924-25). He married Muriel Margaret Burkitt on 9 June 1925 at Holy Trinity Church of England, Dubbo, and then practised medicine at Muswellbrook.

In 1931 John Halliday went to Britain, where he studied for two years at the London Hospital, the Hospital for Consumption and Diseases of the Chest, Brompton, and the National Hospital for the Relief and Cure of Diseases of the Nervous System, Queen Square. On his return to Australia he was appointed to Lewisham and Callan Park Mental hospitals and in 1934 became an honorary assistant physician at Royal Prince Alfred Hospital. His interest in electrocardiography began with his early association with Dr Sinclair Gillies and developed in London. In 1938 he became a foundation fellow of the Royal Australasian College of Physicians, of which he was later councillor (1958-64), vice-president (1964-66) and chairman of the finance committee (1966-71).

On 21 May 1940 Halliday was commissioned in the Australian Army Medical Corps, Australian Imperial Force, and next day was promoted to major. When he embarked for the Middle East in October to join the 2/5th Australian General Hospital, he took a portable electrocardiograph with him and, after his arrival, did cardiac assessment for the British and Australian armies. In 1942 he was repatriated and promoted to lieutenant colonel. He served in Australia until he transferred to the Reserve of Officers on 7 May 1944.

Continuing at Royal Prince Alfred Hospital, Halliday joined (Sir) J. Kempson Maddox and others in establishing (1949) the Hallstrom Institute of Cardiology. He was a medical officer (from 1946) and chief medical officer (1952-64) at the Australian Mutual Provident Society. There he helped to revise the rating system for `substandard lives’, and played a key part in establishing the Life Insurance Medical Research Fund of Australia and New Zealand serving as its first medical director (1953-59). He was a founder (1952) and president (1962-64) of the Australasian Cardiac Society (Cardiac Society of Australia and New Zealand) and one of the committee (1958) that established the National Heart Foundation of Australia. In 1955 he was elected a fellow of the Royal College of Physicians, London. A fine teacher and excellent clinician, he maintained a busy private practice, encouraged the development of younger cardiologists and wrote many papers.

John Halliday was a member of the Union and Royal Sydney Golf clubs. In his younger days he had played good tennis; later he enjoyed golf, bowls and bridge, and was an expert fly fisher. He retired to Moss Vale in the late 1960s but found he was in demand there as a consultant until illness in the mid-1970s caused him to give up practice. With his wife, who had become blind, he later returned to Sydney. Survived by his daughter and two sons, one of whom, Peter, was a surgeon, he died on 27 December 1990 at Elizabeth Bay and was cremated.