Abstract During the early post-war era, a Japanese revival was a source of profound concern to members of the Commonwealth, especially Australia and New Zealand. Britain, having abdicated the leading role in the Western Pacific to the United States, attempted to retain some influence in the region, but economic frailties and lack of Commonwealth unity undermined these efforts. Under American guidance, diplomatic, commercial and (to a lesser extent) security ties with Japan were later promoted, but elements of cooperation and competition persisted in Commonwealth relations with their former enemy. Ultimately, Britain, Australia and New Zealand placed their respective regional identities ahead of their Commonwealth loyalties. Japan took advantage of this situation to promote its own national interests. Hence, the wider aperture of the ‘Commonwealth lens’ throws into sharp relief the contours of a number of members' bilateral relationships with Japan.