This investigation into the life and work of William Henry Clayton, New Zealand's first and only official Colonial Architect, is intended to draw attention to a much neglected major architect. This is, in part, a history of Victorian architecture in Tasmania and New Zealand, but also a record of the contribution of one man to the architectural heritage of these two countries. Some buildings are discussed in detail.There are many buildings possessing breadth of design and boldness of execution which cannot be analysed due to the limited scale of the thesis.