How old-timey ‘skiffle’ music liberated British rock

Singer/songwriter Billy Bragg gained fame as a punk rock and folk musician in the 1980s. Now nearing 60, he’s still singing songs of protest and passion, but also singing the gospel of skiffle, a folk and blues-inspired genre that helped propel a generation of British rockers. Jeffrey Brown sits down with Bragg to discuss his new book, “Roots, Radicals and Rockers.”