This article looks at a particular moment in the relation between popular music and social protest, focusing on the traditional (trad) jazz scene of the 1950s in Britain. The research has a number of aims. One is to reconsider a cultural form dismissed, even despised by critics. Another is to contribute to the political project of cultural studies, via the uncomplicated strategy of focusing on music that accompanies political activism. Here the article employs material from a number of personal interviews with activists, musicians, fans from the time, focusing on the political development of the New Orleans-style parade band in Britain, which is presented as a leftist marching music of the streets. The article also seeks to shift the balance slightly in the study of a social movement organisation (the Campaign for Nuclear Disarmament, CND), from considering it in terms of its ‘official’ history towards its cultural contribution, even innovation. Finally, the article looks at neglected questions around Americanisation and jazz music, with particular reference to power and the past.