Born in Manea, Cambridgeshire, England, on 22 July 1869, Mabel Thurston was the daughter of Mary Ann Green and her husband, Frederick Thurston, a pharmaceutical chemist. She emigrated to New Zealand in 1901 and entered Wellington District Hospital to train as a nurse. The regimen of work – often 11-hour days, seven days a week – meant that only the disciplined and motivated probationers completed the training. Thurston became a registered nurse in December 1904, and moved on to become matron of Grey River Hospital from 1906 to 1908. From there she went to Christchurch Hospital as matron until 1916.
She was a popular matron and a capable manager, considered to be 'sometimes strict and severe', but essentially kind to patients and nurses. Her concern for patients extended well beyond her working day. Late at night she would arrive in a ward to enquire after a seriously ill patient and to check on the nursing care.
Thurston also took an active part in the Canterbury Trained Nurses' Association from its inception in October 1908, and subsequently became a leading member of the national association. Her time as president of the Canterbury branch from 1914 to 1916 was spent confronting difficulties such as the employment by doctors of untrained women to care for their private patients and the conflict between trained and untrained nurses. One of her achievements was the formation of a benevolent fund for trained nurses in times of sickness or financial hardship.
In 1916 Mabel Thurston was offered the position of matron at the New Zealand Military Hospital at Walton-on-Thames, England. She received the support of the North Canterbury Hospital and Charitable Aid Board members, who granted her leave of absence and expressed their deep appreciation of her 'capabilities and services, especially in the training of nurses'. On 17 August 1916 her war duties expanded when she also became matron in chief of the British-based New Zealand Army Nursing Service. Her new duties were to supervise the 430 New Zealand nurses who were members of the New Zealand Expeditionary Force on active duty in England, France and Egypt; organise the supply of nurses to the four New Zealand military hospitals in England; and set the standards of military nursing. It was strenuous work as she, ultimately, had the responsibility for maintaining a New Zealand military nursing presence in England. From January 1917 she worked full time from NZEF headquarters in London. In recognition of her military service Thurston received the Royal Red Cross, first class, in 1917, and was appointed CBE in 1919. On both occasions she attended Buckingham Palace to receive the decorations.
Although Mabel Thurston had been given leave of absence for the duration of the war when she initially enrolled with the nursing service, in 1918 she received a letter from the board indicating that the length of time she had been away had adversely affected the hospital. The letter also implied that the acting matron had turned down offers of other jobs in her desire to remain in the post vacated by Thurston. The quality of Thurston's work during her time at Christchurch Hospital did not appear to be under question; the board's concern was that her absence meant the lack of a co-ordinated nursing service. Thurston responded by saying that she had understood leave had been granted for the duration of the war and that she intended to return to New Zealand as soon as it ended. The board, unmoved, terminated her appointment.
Even after a meeting of concerned citizens in Christchurch castigated it for its gross neglect in the repatriation of war workers, commenting especially on the way it had treated Mabel Thurston, the board showed no inclination to alter its stance. Thurston officially resigned. The furore over her treatment was not quickly forgotten. Two years later, in January 1920, when she returned to New Zealand to take up a position as matron at the King George V Military Hospital at Rotorua, it was publicly noted that the board had given 'scant courtesy to a lady who has borne her part in the war with integrity and credit'. Meanwhile, James Allen, minister of defence, wrote to General A. J. Godley complaining that 'Miss Thurston has not been treated well by the Christchurch Hospital Board.'
Thurston was matron of Queen Mary Hospital, Hanmer Springs, from February 1923 until 1924, and matron of Pukeora Sanatorium, Waipukurau, from 1924 to early 1927. She returned to England later that year. During the Second World War, although retired, she worked as an official visitor for the New Zealand War Services Association, visiting New Zealand soldiers in British hospitals. She never married. One of the few women to hold a prominent senior position in the army during the First World War, Mabel Thurston died in London on 23 July 1960.