The quest for the perfect guitar riff is a noble one – if not quite the key to unlocking the mysteries of the universe

A few weeks ago, my eight-year-old son, who’s taken up the guitar, announced that he’d learned something new. He then played a sequence of chords — approximately, Duh-duh-duuh, Duh-duh-da-duuh — that I’ve been hearing from all guitarists since I was about eight myself. ‘It’s called “Smoke on the Water”,’ he informed me, unnecessarily.