I did a BA dissertation in 1972 on the folk songs of miners as an expression of their culture. I was fortunate to be able to interview AL LLoyd. Folk or home-grown music acts as an expression of hopes, feelings, anger, love, rebellion etc. of oppressed peoples. It's no accident that social movements for change thoughout history have generated songs which both express the struggle and keep up morale. It's also no accident that singers and writers of songs have been murdered or imprisoned by oppressive regimes (eg Victor Jara). In Britain there is a growing network of socialist choirs, many of which sing at political events and demonstrations, sometimes adapting popular songs for specific occasions.