<p>The Rolling Stones' guitarist Keith Richards was cast away by Kirsty Young in 2015.</p><p>He recalls the moment he bumped into his primary school friend Mick Jagger at Dartford train station in 1961, years after losing touch with him. They bonded over a shared love of American blues, which came to define their own sound. Keith Richards laid down the guitar riff for one of the biggest hits, "Satisfaction", on a tape machine in his sleep.</p><p>You can listen to the full episode on BBC Sounds.</p>
