Think of folk music and you think of acoustic guitars, singing with your finger in your ear and sad, tragic stories of failed romance all washed down with a tankard of real ale. However, there’s quite a bit more to it than that. From the Dust Bowl balladry of Woody Guthrie in the 1940s through to Fairport Convention plugging in and rocking out in the 1960s and Laura Marling’s reinvigoration of the singer-songwriter genre in the mid-2000s, folk is a many textured thing, constantly reinventing itself but always staying true to its roots. Here are the 20 best albums ever to come out of folk.