Alan Yentob assesses the career of Mississippi slide guitar legend Robert Johnson and investigates how the instrument evolved rapidly in the 1920s and 30s, when electrification solved the amplification problem. Les Paul recalls the impact of the iconic instrument he designed, which is still produced under his name, while Mark Knopfler and Hank Marvin describe the extraordinary influence of the Fender Telecaster and Stratocaster on performers from Cliff Richard to Jimi Hendrix.