From the 1920s to 1960s it treated mental health conditions generally but in the 1970s it became the national specialist addiction and alcohol treatment centre.

[3] Duncan Rutherford, a local sheep farmer, offered the use of The Lodge Hotel for convalescent soldiers while a new building was constructed.

[3][4][5] In 1915 plans were drawn up for a hospital to accommodate 200 servicemen returning from World War I who needed rehabilitation for mental and nervous conditions, particularly shell-shock.

[3] In the early 1970s Queen Mary became the national hospital for the treatment of addictions, taking patients from all over the country who were referred by their general practitioner.

[12]: 33–34 Around 1989 the Canterbury Area Health Board proposed closing Queen Mary but there was great public opposition, including demonstrations.

[13] The Health Board draft operating plan also proposed reducing the number of beds from 117 to 55 and shortening the courses of treatment.

[14] Fenwick and Beattie planned to bring in private fee-paying patients from New Zealand and overseas to make the hospital financially viable.

From 1999 to 2000 they also set up regional outpatient clinics in Christchurch, Wellington, Tauranga, Hamilton and Auckland which would refer patients to the hospital.

[14] A plan produced in 2003 proposed reducing beds, staff numbers and taking more private patients to enable the residential programme to continue.

[12]: 182–183 [14] He also believed that opposition to the spiritual dimensions of Queen Mary's treatment programmes was another factor in the hospital's demise.

[12]: 182–183 In late 2003 the Canterbury District Health Board proposed selling the hospital land which was now surplus to requirements.

[15] A group of Hanmer residents including Robert Crawford set up The Queen Mary Reserve Trust Incorporated to retain the land in public ownership.

Ngāi Tahu relinquished their option to purchase the land and it passed to the Department of Conservation in 2008 and then to the Hurunui District Council in 2010.

[16][17] In 2012 the Hurunui District Council attempted to lease the buildings, placing the search for tenants with Bayleys real estate company.

[21] Earlier in the year the Council announced that it would restore and earthquake strengthen the Soldiers' Block and use the building as a community space, a meeting house for local iwi Ngāti Kurī and an interactive museum telling the history of the hospital.

[24] From 1921 until the late 1960s men and women with mental health conditions such as depression, psychoses, anxiety disorders and addictions were treated.

[3] Queen Mary was never gazetted as a hospital for compulsory treatment under the Mental Health Act, making all admissions voluntary.

[12]: 33 Treatment was based on Alcoholics Anonymous lines, but later psychotherapies were adopted including group therapy and psychodrama.

[12]: 144–145 Accounts from former patients attest to the effectiveness of the treatment programmes and the healing provided by the beauty and tranquility of the environment, both physical and spiritual.

[16][20][27] The accommodation blocks at the hospital were all designed facing north with views of the mountains; they were built with plenty of windows and verandahs to maximise sunlight and fresh air for the promotion of healing.

[3] Other facilities in the block were hospital administration, the telephone exchange, the central kitchen from 1979, the pharmacy and the Hanmer district's medical centre and operating theatre.

[30] Four poupou (carved posts), from Hokianga, the Bay of Islands and Kaikōura, were donated in 1991and erected at a special hui (gathering).

[30] A 2010 landscape report for the Hurunui District Council listed and assessed the trees and recommended that the spiritual garden be maintained.

[3] A small wooden morgue building, built in 1902, was re-located to the south of the Rutherford Ward in 1957 from its original site near the Soldiers' Block.