The former South British Insurance Building is a fine example of a 1920s 'Chicago-style' office block in central Auckland, complementing the nearby General Buildings. Such high-rises marked a considerable shift in design and business organisation from the smaller, single-tenancy offices used in the mid to late nineteenth century. The change is exemplified by the South British Insurance Company, which transferred its headquarters into this building from its smaller chambers in nearby Queen Street (see 'Blackett's Building') in 1929. The Auckland-based company had been founded in 1872, but expanded its international operations significantly in the early 1900s.

The new building was one of the tallest structures in Auckland, and of self-consciously 'modern' design. The South British company offices were prominently located at street and first floor level, separated from the company boardrooms at the top of the building by several floors rented out to other firms. Although the design was heavily influenced by American prototypes, the British connections of the company were reflected in its employment of English stone cladding and the re-use of a statue of Britannia, which had surmounted the previous South British headquarters in Blackett's Building. The architects - Grierson, Aimer and Draffin - were also involved in the contemporaneous construction of the Auckland War Memorial Museum. The South British occupied the offices until 1982, when the firm was amalgamated with the New Zealand Insurance Company.

The South British Insurance Building is significant as the largest and one of the finest 'Chicago-style' high-rises in Auckland, which reflects the prosperity of one of the city's most prominent financial institutions. It is particularly valuable for its location next to Blackett's Building, showing important changes in commercial architecture and business organisation from the late nineteenth to early twentieth centuries. Its interiors include some of the finest Art Deco ornamentation in the city centre, and it makes an important contribution to the urban streetscape. It is additionally significant as one of a group of buildings in the commercial district that show Auckland's prosperity as a financial centre in the 1920s.