Malcolm Williamson (1931-2003) was one of the most successful Australian composers of the latter half of the twentieth century and the depth, breadth and diversity of his achievements are largely related to his decision to leave Australia for Britain in the early 1950s. By the 1960s, he was commonly referred to as the most commissioned composer in Britain‚ÄövÑvp and in 1975 he was appointed to the esteemed post of Master of the Queen's Music. While his service to music in Britain is generally acknowledged in the literature, the extent of his contribution to Australian music is not widely recognised and this is the first research to be undertaken with a strong focus on the identification and examination of the many works he composed for his homeland and his projection of an Australian identity through his music and persona. This study draws on previously-unexplored primary source material, including correspondence and manuscript scores, to support the assertion that Williamson projected an Australian identity and to provide insight into the construction and manifestations of that persona and the effect that these elements had on the reception of his works. Major works examined in this study include Symphony for Voices (1960-62), The Display (1964), the Sixth (1982) and Seventh (1984) symphonies, The True Endeavour (1988) and The Dawn is at Hand (1989). To place the discussion of Williamson's expressions of national identity in context, the composer's expatriate experience and views of his homeland are examined and compared to the journeys and opinions of numerous other high-profile Australian expatriate creative artists. Significantly, many parallels are discovered that can be interpreted as characteristics of the reverse-migration experience and are indicative of the prevailing cultural attitudes towards Australian expatriates during the twentieth century; confirming that Williamson's situation was not particularly unique. This research has permitted a reassessment of Williamson's creative life and work and as a result, his contribution to Australian music can now be contextualised and more comprehensively understood and acknowledged.