Edward (Ned) Pōhau Ellison was born on 26 November 1884 at Waikanae, near Wellington. Also known as Pōhau Erihana, he was the 11th of 12 children of Rāniera (Daniel) Tāheke Ellison, a farmer, and his wife, Nani Weller (Hana Wēra). Rāniera was the son of an English whaler, Thomas Ellison, and Te Ikairaua (Te Ikaraua), the daughter of Te Āti Awa chief Te Whati. He was notable for discovering gold on the Shotover River and later became a staunch convert of the prophet Te Whiti. Nani was the only child of Edward Weller, who had established a whaling station in Otago in 1831, and Nīkuru, daughter of Ngāi Tahu chief Te Mātenga Taiaroa. Ned's elder brother, Thomas Rangiwāhia Ellison, became a lawyer and captained the first official New Zealand rugby team in 1893.
As an infant, Ned Ellison was adopted by his father's cousin Harirota and her husband, W. H. Eyes. He was raised on a small dairy farm at Pūnehu, Taranaki, and visited Parihaka, where he met Te Whiti and Tohu. Ned was strongly influenced by the numerous Māori funerals that passed by the farm and he attributed many of the deaths to 'tohungaism'. This later influenced him to choose medicine as a career. After the death of Harirota in the mid 1890s Ned returned to live with his parents, first at Waikanae and then at Ōtakou on Otago Peninsula.
Ellison was educated at Pīhama, Waikanae and Ōtakou schools before entering Te Aute College in 1902. He was a keen rugby player, and was also active in the Te Aute College Students' Association and later the Young Māori Party. He was converted to Christianity before matriculating in 1904, and furthered his religious studies at Te Rau Theological College, Gisborne, before deciding to pursue a medical career. Unable to secure financial assistance from the government or his family, he found work with a survey party in Otago, before returning to Te Rau College. During this time he represented Poverty Bay at hockey, and in 1911 he was selected for the New Zealand Māori rugby team.
Ellison studied science at the University of Otago in 1912–13 and in 1914 entered the Medical School. He continued to excel at sport, representing the university at rugby and cricket. On 30 July 1913 he married Tini Wīwī Taiaroa at Sedgemere, Christchurch. Her father, Te One (John) Wīwī Taiaroa, was a prominent Ngāi Tahu leader and had been a member of the 1884 New Zealand rugby team.
Ellison graduated MB, ChB in 1919, and that year was appointed chief medical officer for Niue. During his four years there he held numerous other positions, including deputy and resident commissioner, resident magistrate, coroner, sheriff, and chairman of the licensing committee. In 1923 he became medical officer and resident magistrate for the Chatham Islands.
In 1925 Ellison returned to Otago University to undertake postgraduate studies in tropical medicine. He travelled to Samoa and then to Makogai island, Fiji, where he wrote an important paper on leprosy. The following year he was appointed chief medical officer and deputy resident commissioner to the Cook Islands. Tragedy struck on 18 September 1926 when his wife, Tini, died suddenly of acute rheumatic fever, leaving a young family of two sons and a daughter. Another daughter had died earlier.
In 1927 Ned Ellison was recalled to New Zealand to replace Peter Buck as director of the Division of Māori Hygiene in the Department of Health. Working closely with Māori leaders such as Sir Apirana Ngata, Ellison wrote a series of articles in the journal Te Toa Takitini advising on the treatment of dysentery and influenza, and represented the department at a number of important hui. His experience of treating typhoid in the Pacific islands proved valuable in dealing with the disease in New Zealand. During one outbreak near Te Kaha, when the source proved difficult to trace, Ellison was convinced that the water supply was at fault; only after intensive testing was this confirmed. On another occasion, when he was asked to investigate a serious outbreak near Rotorua, he advised dietary and sanitary improvements that quickly eased the problem. He also worked with the Census and Statistics Office to collect more accurate statistics on Māori health.
On 12 July 1928, in Wellington, Ellison married Mary Karaka Boyd; they were to have four sons and two daughters.
In 1931 Ellison was reappointed chief medical officer to the Cook Islands, a position he was to hold for the following 14 years. He also served as commissioner of the islands' High Court from 1932. He faced extensive health problems with very limited resources. Tapeworm disease, endemic in the islands, he dealt with through mass inoculations and improved ground sanitation with the financial assistance of the Rockefeller Foundation. He also set up a child welfare programme, which involved health nurses visiting remote villages, and he presented the Ellison Cup to the village with the best child welfare record.
Ned Ellison was an outstanding administrator with strong leadership qualities. In 1934, when a hurricane severely damaged Rarotonga's port and hospital, Dr F. W. W. Dawson was sent from New Zealand to deal with the disaster. By the time he arrived, however, reconstruction work was well in hand and the hospital had been reopened. Ellison promptly used Dawson's ship to collect lepers and transport them to a remote island. On another occasion he dealt with a dangerous outbreak of German measles by converting churches and schools into temporary hospitals, staffed by teachers and missionaries. Patients were transported to these hospitals, thereby avoiding the common local treatment – cold showers – which frequently proved fatal. Ellison also introduced a programme to eradicate mosquitoes by removing stagnant water from around homes; this helped to reduce the incidence of filariasis.
Ellison received the King George V Silver Jubilee Medal in 1935 and in 1938 was appointed an OBE for his long and dedicated services to the Polynesian people. He returned to New Zealand in 1945 and took up private practice in Manaia, Taranaki, where he and Mary became actively involved in community and sports groups. In 1953 he received Queen Elizabeth II's Coronation Medal. Ellison retired to Taradale, Hawke's Bay, in 1956, and died in Napier on 9 November 1963. He was survived by Mary and nine children of his two marriages.
Edward Pōhau Ellison was a big man, both physically and in ability and moral character. He is remembered for his devotion to the people of Polynesia, his administrative skills, and his strong, determined and often obstinate character. His Māori background afforded him a greater insight and understanding of Polynesian ways. Although he was never in the forefront of political activity, in his own quiet, persuasive way Ellison made an outstanding contribution to the health of the Polynesian people.