To serve the British nation in World War II, the BBC charged itself with mobilizing popular music in support of Britain's war effort. Radio music, British broadcasters and administrators argued, could maintain civilian and military morale, increase industrial production, and even promote a sense of Anglo-American cooperation. Because of their widespread popularity, dance music and popular song were seen as ideal for these tasks; along with jazz, with its American associations and small but youthful audience, these genres suddenly gained new legitimacy at the traditionally more conservative...