T. Rex were going for their fifth number one with Children Of The Revolution but had to settle for their third No.2 instead.

By September 1972 T. Rex had already had four number ones so you’d have bet your house on the next single joining them at the top of the chart. You’d have lost it because pretty-boy David Cassidy put paid to that with his cover of The Young Rascals hit How Can I Be Sure.

So Children Of The Revolution stalled at No.2.

It’s got a monolithic guitar riff to place up there with the likes of Smoke On The Water and Sweet Jane and Satisfaction. Undeniably heavy metal. But the song is more of a pastiche of heavy metal, thanks to Bolan who camps it up like never before on this TV appearance, as if to mock the heavy metal merchants of the era – Purple, Sabbath, Zeppelin – by demonstrating that the more macho the music becomes, the more androgynous he will be.

Of course it has the one lyric everyone remembers when they think about T. Rex – “I’ve got a Rolls-Royce / ‘Cos it’s good for my voice” – and a few others: “You can bump and grind / ‘Cos it’s good for your mind” and “You can twist and shout / Let it all hang out.” But for all that bumping, griding, twisting and shouting in your Rolls-Royce (hello John Lennon with your champagne Maoism!) you won’t fool the real children of the revolution.

Of course it’s meaningless – delightfully, wonderfully, joyfully, memorably meaningless. Like all the others. But it’s also a celebration of the musical revolution that Glam began, leading inexorably to punk a few years down the line when the children (me!) grew up and started a revolution of their own.

Here is the very different version from the Born To Boogie film, featuring Elton John playing some rollicking honky tonk piano, and Ringo Starr on drums.