Truby King House (Former) in Wellington was designed by the pre-eminent architect William Gray Young in 1923 for the co-founder of the Plunket Society, Frederic Truby King [1838-1938].

Born and raised in New Plymouth, King trained as a doctor in Edinburgh, England. While in England, he married Isabella Cockburn Millar. The Kings moved to New Zealand in 1887 and together established the Plunket Society in 1907. Named after its patron, Lady Victoria Plunket, wife of the then Governor-General, the society aimed to reduce the high infant mortality rate through the promotion of breastfeeding, domestic hygiene and strict adherence to routine. Plunket clinics and 'Karitane' hospitals were opened throughout the country and by 1930, 65 per cent of all non-Māori infants were under the care of trained Plunket nurses. By 1947 this figure had risen to 85 per cent. Truby King was awarded a Companion of St Michael and St George in 1917 and was knighted for his services to health in 1925.

Between 1924 and 1932 Truby and Isabella King lived in the house, with their daughter Mary. The house, located on the top of a hilly section at Mount Melrose, was constructed by Wilson and Johnson of Kilbirnie, in 1924. The design of the single storey timber building shows influences of the American bungalow and colonial styles. The house included a formal public wing for entertaining dignitaries to the west, and private living spaces to the east. The geographic positioning and spatial layout of the house maximised sun and light exposure to the northern elevation, illustrating King's ideas about the importance of the environment on people's lives.

The house included a study for King, which featured a specially designed sliding window that allowed King to set up a telescope and take full advantage of the spectacular views over Wellington. The study was also home to King's vast personal library, which included thousands of books that covered a vast range subjects and authors:

almost every topic is represented, from opera to classical mythology, all the great authors, many travel books, one New Testament and a child's bible. There is no 'light' reading. The only novels are serious classics, and there are no books on sport.

The books provide a fascinating insight into some of the influences on King, especially medicine and health, and also plant husbandry.

While the house provided spectacular views, it was also at the mercy of the natural elements - particularly the wind, and Mary King relates stories of visitors to the house having their umbrellas turned inside out during visits! To deal with this, King designed and constructed a number of wind screens around the house, made of a mesh material which alleviated the wind, but did not break the views, leading King to claim 'there was always one side of the building that was totally sheltered.'

In 1924 the Kings commissioned Young to erect a Karitane Hospital down the hill on the site of their former tennis court. Their four hectare [10 acre] section was developed into a blossoming garden with brick paths and pergolas to 'provide an intangible sense of refreshment, regeneration and recreation' for the mothers staying in the hospital.

In 1927 Isabella King died, and in 1932 King announced that he was gifting his house to Plunket Society. He then shifted into a flat at 42 Sutherland Crescent. He then moved back into his former house, where he spent a short time under the care of a nurse until he passed away in February 1938. King was buried in the Melrose garden on an elevated section that had originally featured a pergola. On the suggestion of the then Minister of Health Peter Fraser, he was honoured with a state funeral, the first private citizen in New Zealand to receive such a tribute. The remains of Isabella King, the mainstay behind King's work, were transferred to the Melrose site from their original resting-place in a cemetery in Porirua.

Upon King's death the Plunket Society took over the house and land. The house was used by Plunket Society initially, and was commandeered by the army during World War Two. In the 1960s it was used as a convalescent and nurses home for a period, before being reused by Plunket Society as an office for their Deputy Director of Nursing.

The house remained close to its original condition, though a number of small modifications were made over the years. These included the construction of a garage under the west side of the house in 1935, the filling in of part of the northern verandah and the southern porch, and the combining of two of the bedrooms. In 1979 a caretaker's flat was built in the former service rooms in the south-west of the house.

During the 1970s, as the Plunket Society faced increasing financial difficulties, the house became increasingly run down and suffered neglect. To remedy this, in the late 1970s Plunket Society tried to raise money for maintenance and restoration work, and began making repairs - though there were questions over the authenticity of the work being done.

By 1988 Plunket Society had sold all the land and buildings of the original Mount Melrose estate, bar Lot 2 DP12962 which encompassed the house and mausoleum, which it seems Plunket Society had been intending to further subdivide. In August 1988 at a public meeting it was suggested the Wellington City Council purchase the remaining parcel of land, and negotiations began between the City Council, Plunket Society and the owners of the adjacent land. In 1990/91 the Wellington City Council purchased Lot 2 DP 12692 from the Plunket Society, taking possession of the land containing the house and mausoleum, to go with the other parcels of land that make up the current historic reserve. The Council undertook much needed repairs on house, including fire proofing improvements in 1993/94, and new roofing in 2005. The paths and driveways around the house were also re-graded and re-asphalted, and the brickwork was repaired with original bricks made in Miramar in the 1920s. In 1991/92 there was a period of public consultation and research to devise a draft management plan, and there were a number of suggestions put forward for use of the house during consultation phase. However, the house remained in Council possession and has since been leased to various tenants. While major restoration work on the house has not yet gone ahead, it remains in good condition.

The Truby King House is recognised for its architectural and historical significance.