Alfred Peter Hillier went to school on the Isle of Man and in 1874, at the age of 16, arrived in the Cape Colony. He gained some experience of ostrich farming and continued his studies, obtaining the Bachelor of Arts (BA) degree from the University of the Cape of Good Hope in 1877. During the Ninth Frontier War of 1877-1878 he served as a trooper in Bowker's Rovers. Returning to Britain he qualified as Bachelor of Medicine (MB) and Master of Surgery (CM) at Edinburgh in 1882, and as Doctor of Medicine (MD) at Edinburgh in 1884. He must have planned to return immediately to the Cape Colony, for he was licensed to practice there in October 1883. Settling in East London he became assistant to Dr J.H. Paley for two years, as well as surgeon to the Kaffrarian Rifles and Frere Hospital. In 1885 he married Mary Ethel Brown, with whom he had two daughters and a son.
Hillier was a man of wide interests, including archaeology. He collected some stone tools near East London and excavated a shell midden near the mouth of the Buffalo River, donating some archaeological material to the British Museum in 1887. In November 1886 he wrote a paper, "The antiquity of man in South Africa, and evolution", that was read on his behalf before the Eastern Province Literary and Scientific Society in Grahamstown and published in the Grahamstown Journal (23 and 25 November 1886). After a brief review of stone tool archaeology in Europe he described archaeological finds in South Africa in general terms, particularly those of George McKay* around East London, and including some of his own observations. He mentioned, among others, artefacts that appeared to be associated with raised beach deposits on the west bank of the Buffalo River, suggesting variations in sea level as well as the antiquity of humans. Though not of great importance, the paper was republished several times, with some revisions: In the 1887 New Year edition of the East London Dispatch, as a pamphlet in Kimberley in 1890, and in Hillier's book Raid and reform... in 1898.
Hillier moved to Kimberley as resident surgeon at the Kimberley Hospital and then entered a partnership with Dr L.S. Jameson (of Jameson Raid fame), whose practice he took over in 1889. He became a leading medical practitioner in the town, being elected president of the Griqualand West Branch of the British Medical Association in 1892 and acting as president of the First South African Medical Congress, which met in Kimberley during May 1893. Although he was a Fellow of the Edinburgh Obstetrics Society, his publications dealt with other aspects of the medical field, including a note on the removal of a piece of cartilage from a patient's knee joint (South African Medical Journal, Series 1, 1886, Vol. 2, p. 78), and a paper on "The physiological effect of altitude in health and disease" (South African Medical Journal, Series 2, March 1894). He followed the latter paper up by delivering "Further notes on the physiological effect of altitude in health and disease" at the February 1895 meeting of the Transvaal Medical Society.
In 1893 he was admitted to practice in the South African Republic (Transvaal). He moved to Johannesburg where he set up a practice, though he also developed an interest in finance and politics. His literary flair led to the publication in 1894 of a work of fiction, In the veldt, under the pseudonym "Harley". The refusal of the government of the South African Republic to grant local autonomy to Johannesburg and meet the requests for reform of its English speaking population led to Hillier's participation in public life as a member of the Committee for Education and other public committees. He also became a member of the Reform Committee, which plotted the overthrow of the Republic's government. After the failure of the Jameson Raid during the last few days of 1895 he was arrested, but fined and released a few months later. He wrote up his experiences during these times in the form of a book, Raid and reform by a Pretoria prisoner (1898), and two years later published his South African studies (1900). He also contributed long articles to the Encyclopaedia Brittanica (10th edition, 1902-1903 and 11th edition, 1911) on the history of South Africa, the Transvaal, the Orange River Colony and Cape Colony.
In 1897 Hillier left for England and practiced in London to his retirement in 1906. He had a particular interest in tuberculosis and was nominated by the Prince of Wales (later King Edward VII) as one of the delegates of the National Association for the Prevention of Consumption to an international congress on the disease held in Berlin in 1899. In 1900 he published Tuberculosis: Its nature, prevention and treatment. Three years later he wrote a more popular text, The prevention of consumption (1903), the manuscript of which had been revised by the eminent bacteriologist Robert Koch*. Hillier was secretary to the (British) National Association for the Prevention of Consumption, consulting physician to the London Open Air Sanatorium, and a member of the International Bureau for the Prevention of Tuberculosis.
He served on the London committees of a number of well-known gold mining companies that were active on the Witwatersrand. As a councillor of the Royal Colonial Institute he published a paper in its Proceedings on "The native races of South Africa" (1898), which dealt with the Bushman, Hottentot and Bantu races and the effect of European colonists on their culture. In the same year he wrote a pamphlet on "The climate of South Africa". In 1900 he was elected as a Unionist member of the House of Commons for Stockport. He was re-elected as a member for South Bedfordshire in 1904, lost the seat two years later, and was elected as the Unionist member for Hitchin in 1910. In 1909 he published The commonweal; a study of the federal system of political economy. However, in 1911 he committed suicide.