We're all familiar with rock music's living legends, but perhaps more intriguing are rock and roll’s cult heros - the artists who've inspired other artists without getting massive rewards. Wilko Johnson fits that bill. His raw guitar sound in the band Dr Feelgood paved the way for punk, and he kept on rocking through cancer, depression and changing musical tastes. In 2017, he spoke to Stephen Sackur about what kept him going.(Photo: Wilko Johnson in the Hardtalk studio)