Elizabeth Ralston Fergusson was born on 16 April 1867 at Balligmorrie, near Barr, Ayrshire, Scotland, the daughter of Eliza Ralston and her husband, James Fergusson, a farmer. Elizabeth's mother died when she was three but nothing else is known of her life before she began her nursing training at the Bristol Royal Infirmary in 1894. She was awarded the diploma of the Obstetrical Society of London in 1897, then worked as a private nurse for three years. During the South African War she served from 1900 to 1902 with Britain's Army Nursing Service Reserve. Later in 1902 she emigrated to New Zealand; by this stage she was known as Elizabeth Leila Ralston Fergusson.
Fergusson was registered as a nurse in New Zealand in November 1902, and over the next five years she nursed at a private hospital in Wanganui. From 1907 to 1912 she worked in the backblocks in charge of the Ruanui Maternity Hospital at Taihape. Initially the hospital also provided emergency services for people involved in the construction of the main trunk railway line.
In 1912 Fergusson shifted to another remote location to become matron of the Bay of Islands Hospital, at Kawakawa, Northland. She remained there for two years and it is said she did fine organisational work. In December 1914 she took up the position of native health nurse for the Mangonui district. Most Maori in the area were unfamiliar with European medicine, either curative or preventive. Their general standard of health was poor and there were frequent outbreaks of typhoid fever and a high incidence of other infectious diseases such as tuberculosis, diphtheria and scabies.
The Maori health nursing service was still relatively new at the time and funds and auxiliary support for the nurses were scarce, especially during the First World War. Consequently the Department of Public Health was unable to provide suitable accommodation for Fergusson at her base in Kaitaia. Undaunted she purchased a block of land big enough to graze her horses and built herself a cottage. It is claimed she did all the labour herself, including putting on the roof. Amelia Bagley, supervisor of the native health nurses, wrote that it was 'an unequalled example of what a woman can accomplish if she so desires'.
The district Elizabeth Fergusson covered as a nurse was enormous, extending from Whangaruru in the south-east of the Bay of Islands to Te Hapua in the far north. To make her trips easier she acquired an old horse-drawn ambulance from the Bay of Islands Hospital and converted it into a caravan for carrying camping equipment, food and medical supplies. She was accompanied on her regular visits around the district by her assistant, Gladys Kidner. The two women, with the help of the schoolteacher and some local Maori, built their own depot cottage at Te Hapua. Fergusson raised funds for the project by holding jumble sales where she sold warm clothing that had been donated by her friends.
In addition to the problems of accommodation and transport Fergusson had to cope with language and cultural differences. Her concern went beyond immediate cures and treatment to providing instruction in health and hygiene. In 1920 Amelia Bagley likened this aspect of her work to 'wayside sowing' that quite frequently 'takes root'. Fergusson was always on call, often working for weeks without a break, beginning at 4 a.m. day after day. That she was able to continue in her position for 12 years says much for her courage, energy and adaptability. By the time of her retirement at the end of 1926, her name had become a household word in the far north.
Soon after her retirement Fergusson moved to Brunswick near Wanganui where she and Gladys Kidner purchased a poultry farm. Elizabeth Fergusson died of heart failure on a train at Marton on 12 February 1930. She had never married.