“20th Century Boy” by T. Rex

Marc Bolan's "20th Century Boy" came out as a single on its own in March 1973. It was at one point lined up to close Tanx, but it stayed off the album until the 1985 reissue tacked it on as a bonus. T. Rex cut the basic track at Toshiba Recording Studios in Tokyo on 3 December 1972, in a session that ran from mid-afternoon into the small hours, and Tony Visconti, who still gets the production credit, was apparently absent for once: Bolan and Mick O'Halloran took the producer's chair. Back in England after the tour, the backing vocals, handclaps, acoustic guitar and saxophones were piled on.

It's glam at its most brazen, a riff like a boot through a shop window with Bolan preening on top. The single fades at three minutes and 39 seconds, but the tapes kept rolling for close to three more minutes of jamming, which a rough mix on the Bump 'n' Grind compilation finally let out.

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