The Retreat is an early Northland residence, which is closely associated with Henry Williams (1792-1867), a leader of the Church Missionary Society (CMS) in New Zealand. Williams was an important force in efforts by the London-based CMS to convert Maori to Christianity, and also helped to formulate the Maori versions of the 1835 Declaration of Independence as well as the 1840 Treaty of Waitangi - New Zealand's founding document. Built in 1850-1852, the timber dwelling was erected for Williams and his wife Marianne (1793-1879) on their family estate at Pakaraka in the Bay of Islands. It was constructed soon after Williams had been dismissed from his position as the leader of the CMS mission at nearby Paihia. Williams' departure was due to complaints about his purchase of the Pakaraka estate from Maori in the 1830s, of which 3,645 ha (9,000 acres) remained in family hands. Much of this land had been intensively farmed in previous centuries, with a network of Maori fields and settlements on the fertile soils surrounding Pou E Rua pa.

Named 'The Retreat' by Williams, the new house was surrounded by fields on which the family raised cattle and other animals, and had experimented with imported crops such as wheat. The residence lay immediately next to the house of Williams' son, Henry junior (1823-1907), and opposite a church that Williams also erected in 1850-1851 (see 'Holy Trinity Church, Pakaraka'). Reinstated by the CMS in 1854, Williams based his later missionary activities from The Retreat, which he occupied until his death in 1867. The house continued to be lived in by his wife for a further twelve years.

Large and well-appointed for its time, the single-storey residence was constructed in a symmetrical Georgian style. It appears to have been similar to Henry Williams junior's house, having a hipped roof and a verandah on at least three sides. Sited in 1.2 ha (3 acres) of grounds, its main frontage faced away from Holy Trinity Church towards open estate land. An avenue of trees was planted to the original rear of the dwelling, leading directly to the church. The weather boarded structure was erected with internal walls and ceilings of lath and plaster, building on the expertise that Williams gained at Paihia in 1828, when he claimed to have created the first plastered ceiling in New Zealand. The residence included a parlour, bedrooms and a windowless chamber reputedly used by Mrs Williams for delivering local babies. The building was considered expensive to construct, a factor ascribed by Williams to the high cost of labour. A Maori workforce prepared at least some of the timbers, while Henry Williams himself erected one of the brick chimneys.

The pastoral atmosphere of The Retreat was enhanced by the addition of a glass conservatory by the 1870s, while further exotic trees were planted in the gardens. A road (now State Highway 1), however, was constructed dividing the dwelling from the church. When the first Liberal Government (1891-1912) sought to break up large rural landholdings, family members sold off parts of the estate, including the area around the house in 1906. In 1908 the house was transferred to the Anglican Church, who leased it to a succession of tenants. A timber service wing at the current back of the building (originally the front) is said to have been a small cottage or farm building transported from elsewhere on the estate, possibly at this time. Other modifications reflect changing attitudes to living standards in the 1950s, and have included the construction of a bedroom wing, which was later employed briefly as a tearoom. The house is now a private residence owned by a Williams family trust.

The Retreat is nationally significant for its links with early missionary activity in New Zealand, and Henry Williams in particular. It has connections with important events in New Zealand's constitutional history, including the Treaty of Waitangi and earlier developments, of significance to Maori and Pakeha. The building is notable for its association with the establishment of large, privately-owned estates in pre- and early colonial New Zealand, and their use into the late nineteenth century. It demonstrates the importance of family networks during the initial stages of Pakeha settlement, and the complex links between spiritual and material life within a prominent missionary family.

The dwelling, including its service wing, contains evidence of early colonial construction techniques, with its lathe and plaster elements being of particular importance due to Williams' role in early experimentation with this form of construction in New Zealand. The building's physical fabric also potentially reflects significant aspects of social history, including the role of women in early rural healthcare. The structure is part of a broader historic and cultural landscape, demonstrating changes in land use and ownership from pre-colonial to recent times. The building is closely associated with other historic structures, including nearby Holy Trinity Church, as well as archaeological sites such as Henry Williams junior's house, and nineteenth-century plantings.