While Derek and the Dominos' Layla is heralded for its electric guitar riff, its cinematic piano outro is considered by many fans to be a classic contribution to the iconic rock song in its own right.

As backstories go it's up there with the best: mercurially-gifted superstar guitarist with a passion for the blues falls hopelessly in love with the wife of his best friend, an ex-Beatle, then writes ...