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.

Of course, any sign that the world hasn’t changed as much as we thought is always welcome to the middle-aged man. Yet when I showed him Deep Purple performing the whole track on YouTube, he was both slightly bored and rather mystified. Not only had he no idea that ‘Smoke on the Water’ came with a song attached, but he couldn’t understand why it needed one.

This ability of a guitar riff to float free of its origins was among the points made by The Joy of the Guitar Riff, one of those BBC4 music documentaries that, for all their moments of minor — and not so minor — irritation, can generally be relied on to rescue Friday night telly in the absence of Have I Got News for You.

On the whole, the programme took a chronological approach — although not as thoroughly as you might have expected from the opening claim by Tom Morello of Rage Against the Machine that ‘Beethoven’s Fifth Symphony contains one of the great riffs of all time’. From there, we leapt forward exactly 150 years to the song that we were told started it all. Before ‘Johnny B. Goode’, the main instrument in rock’n’roll was the piano. But then Chuck Berry had the bright idea of playing boogie-woogie on the guitar — which, as various grizzled old rockers testified, proved revolutionary.