Across the globe, music has been an essential rallying-cry of revolution and social change: from the Marseillaise to Strange Fruit, from classical symphonies to hip-hop, music has accompanied some of the most vital changes to our world. How does music do it? Peggy Seeger, folk music icon and protest-song-writing genius, tells us how her life in music has been a clarion call for political and social activism, and writer and broadcaster Kevin LeGendre charts the story of music's role in the Civil Rights movement, from the 1960s to today. And through the music of Shostakovich and Prokofiev, we hear what happens when revolutionary fervour curdles into something darker: when does music protest a regime, and when does it support tyranny? A century and more of musical protests and revolutions on The Listening Service at the BBC Proms presented by Tom Service.