This house has great local significance for its association with two prominent members of the Hutt Valley community, George Manly Yerex and Sir David Ewen, and for its unusual architectural style. The house was built for George Manly Yerex and his family in about 1899/1900. George Yerex, a Canadian by birth, had immigrated to New Zealand in the late 1880s and set himself up as an importer of American goods, later forming the Wellington-based firm of Yerex and Jones. He was also a prominent advocate of the New Zealand temperance movement in the 1890s and early 1900s. In 1889 George acquired land on the western hills overlooking the Lower Hutt valley. It is probable that another house (still on the property) had already been built when he bought the site. In the following year he married Clara Pinny. Here Clara and George were to have seven children. In about 1899 George and Clara began building the house that is the subject of this registration.

The style of the house can be described as American Queen Anne, reflecting Yerex's admiration for things American, and his wide overseas experience. It is a large two-storeyed building, with a three-storyed hexagonal turret, and steeply pitched roof. There is some evidence to suggest that the architect may have been William Crichton, a notable Wellington-based architect. The house was named Keewaydin, and at the time it was constructed would have formed an impressive landmark on the almost bare western hills of the Hutt Valley.

The Yerexs remained in the house for only six years, during which time George Yerex served on the Lower Hutt Borough Council (1905-1907). In 1906/1907 the Yerex family moved to Tauranga and later America. One son, Franklyn, remained in New Zealand, and was later noted for his work as a deer hunter and for his principal role in establishing the Wildlife Branch (later Division) of Internal Affairs. Another son, Lowell, after serving in World War I as a pilot, went on to found TACA (Transportes Aereos Centro-Americanos), an international airline servicing Central America.

In 1907 the house, and a portion of the adjoining section, which had been acquired by the Yerexs in 1903, was sold to William Brown. Very little is known about Brown, except that he was a managing director for Laery & Co., produce auctioneers and general importers, who had their offices in Allen Street, Wellington. In 1919 Brown sold the property to another prominent identity, David Alexander Ewen (1884-1957), a businessmen in the firm Sargood, Son and Ewen, and, later, a Lower Hutt Borough Councillor (1923-1925), and his wife Marian. They renamed the house Lochaber. During the 1920s Ewen campaigned strongly for the replacement of the then-decaying main road-bridge over the Hutt River, and a new concrete bridge was eventually opened in 1929. In recognition of Ewen's campaign the bridge was named the Ewen Bridge. This name has remained ever since, although the bridge has again been replaced. In 1934 David Ewen became the first government appointee to the newly formed Reserve Bank and, from 1941, a director of the Australian Mutual Provident Society (AMP). He was also a keen supporter of the Boy Scout Movement in New Zealand, and a governor of Rotary New Zealand. He was president of the New Zealand Academy of Fine Arts, and, until his death, was a member of the board of trustees of the National Art Gallery and Dominion Museum. Ewen was made a Knight of the British Empire in 1952.

During the Ewen's ownership several alterations and additions were made to the house. The original weatherboards were covered over with stucco, and the porch and verandah glassed in. The Ewens also redesigned the garden. In 1976 the Ministry of Works acquired the property for roading purposes, but Lady Marian Ewen, by then widowed, continued to lease the house. In 1982 the house was leased to Prospect College, a small Christian school founded in 1967, which has occupied the property ever since.

Lochaber/ Prospect College is one of only a few large homes known to date to the beginning of the twentieth-century remaining in Lower Hutt. It is historically significant for its association with the Yerex family, and particularly George Manly Yerex, a notable Canadian-born businessman in Wellington. It has special historical significance for its association with Sir David Ewen, local government politician and successful businessman. Architecturally the house is significant for its American Queen Anne design, a style of house relatively rare in the Wellington area.