Enid Marguerite Hamilton Kelly was born in Hamilton on 12 September 1903. Her father, Arnold Joseph Kelly, was a plasterer born to Irish Catholic immigrants. Enid's mother, Annie Maria Elliott, was of Northern Irish heritage and raised her children as Protestants. Enid was the eldest child, having five younger brothers. After the family moved to Auckland about 1908, she attended Grey Lynn primary school until standard six, then completed a part-time office training course while working for the family business.
In 1922 she moved to Rotorua to nurse wounded First World War veterans. There she met Kouma Te Omeka Whakamutunga Ngaherehere Tapsell (Tapihana), a former Maori All Black, who was rehabilitating from injuries sustained at Gallipoli. Kouma, through his father, Retireti (Retreat), was a descendant of the trader Phillip Tapsell and Ngati Whakaue woman of mana Hine-i-turama. Through his mother, Ngatai Pekamu Winiata, he was descended from Te Arawa warrior leader Tohi Te Ururangi.
Against both families' wishes Enid and Kouma were married at St Luke’s Church, Rotorua, on 29 November 1924. Immediately after, they moved to the Bay of Plenty coastal fishing village of Maketu to live with Kouma's relations, known as Te Whanau-a-Tapihana. Enid was one of the few Pakeha women in the area. Rejected at first, she soon won over her in-laws with her many skills. For the next 30 years she was constantly called upon to assist as a midwife, nurse, social worker, dressmaker, marriage counsellor, legal witness and financial advisor. Although short (only a little over five feet) she had a very authoritative presence, a strong will and a spirited determination to gain justice for the underprivileged. She generally dressed practically, often wearing trousers on occasions requiring manual work. She is also remembered for her bright floral dresses, colourful hats, endless cups of tea and her love of dahlias.
From the late 1920s Enid managed a transport contracting business. It ceased operation during the depression, when Enid and Kouma were unable to keep up payments on the vehicles. About this time she was pivotal in assisting Taiporutu Mitchell and Apirana Ngata to secure Te Arawa's acceptance of the Maori lands development scheme in Maketu.
Tuberculosis was rife in the Maketu community and Enid despaired at the government's detached attitude towards Maori health and sanitation. As secretary for the Maketu Welfare League she wrote numerous letters to ministers and officials in an effort to draw attention to the social and economic hardships being experienced by Maori war veterans and their families. Lack of response motivated her to join forces with her friend the mayor of Tauranga, Lionel Wilkinson, and form a short-lived political organisation, the Union Party.
Enid became skilled in the Maori language, which provided her with access to Te Arawa's rich oral traditions. In the 1930s, while raising her five sons, she found time to write numerous short stories. Her first published book, Historic Maketu, which was illustrated by Harry Dansey junior, was published in 1940 as part of the centennial celebrations at Maketu. Enid was also instrumental in organising the construction of the road below the old Maketu pa and building the Te Arawa monument at Ongatoro, which she arranged to be opened on 2 January 1940 by government and tribal dignitaries.
From the 1940s onward her numerous articles and short stories on all aspects of Maori culture were reproduced in local and national newspapers and journals. In 1947 she became one of the very few women to have been published in the Journal of the Polynesian Society; her article was a study of the last surviving species of old Maori kumara still growing in the Bay of Plenty. In the 1940s and 1950s she was not only the Bay of Plenty Times correspondent for the Maketu district but also is said to have written some 100 radio scripts on Maori culture, women's life and natural history. Her series, ‘The Maori way of life today’, was broadcast in Samoa.
On 7 November 1949 Enid Tapsell was made a justice of the peace. In 1953 she moved back to Rotorua, along with Kouma and two of their sons, to live on Hine-i-turama's ancestral land in Te Koutu. In 1955 she became one of the first women in New Zealand to chair a local justices of the peace association and to sit on a magistrate’s bench.
From the early 1930s Enid had maintained a regular correspondence with the Auckland and Wellington museums about Maori culture, native flora and marine life. She became concerned that the Auckland Institute and Museum, the primary repository for collections from the Bay of Plenty, was too far away to benefit its originating community. As principal founder and committee member of the Historical Section of the Royal Society of New Zealand (Rotorua branch), she created Rotorua's first museum inside the old Regent Theatre building. She later convinced her fellow civic leaders to relocate the museum in the old government bathhouse. In 1962 Enid Tapsell became one of the first two women to be elected to the Rotorua City Council.
After the Second World War her husband, Kouma, became the elder spokesman for Te Whanau-a-Tapihana in Te Arawa; he died in 1964. In 1968 Enid's own health deteriorated and she decided not to run for a third term on the council. However, she continued to be very active and commuted between Sydney and Rotorua to research her numerous writing projects. Her unpublished manuscripts include radio plays and historical scripts, biographical stories, and a social study of Maketu. In 1972 she published A history of Rotorua. Enid's final project was to write a book on Phillip Tapsell, but crippling arthritis and failing health prevented its completion. She died at the home of her son, Mark, in Sydney on 5 May 1975. Enid was brought back home and given a full tangihanga at Whakaue marae, Maketu. She was buried at Wharekahu alongside other members of the Tapsell family.