Book excerpt: Marks the centenary of the posting of the first Australian High Commissioner in London, so beginning what is today Australia's oldest diplomatic mission. In 1910, when Sir George Reid was appointed its first High Commissioner in London, Australia was a self-governing but not yet sovereign state and the Australian Governor-General remained the most important channel of communication between the Australian and United Kingdom governments until the late 1920s. The book traces the history of the office and in doing so illuminates the larger story of Australian-United Kingdom relations in the twentieth century, the evolution of Australia from British colony to sovereign state and the gradual transition of the United Kingdom from head of an empire to member of the European Union.