A year later, they'd slimmed down, found a new name and invented heavy metal. Few bands are so inextricably linked with a musical genre, but Sabbath set the template for everyone from Motörhead and AC/DC to Metallica and Guns 'n' Roses.

But the tune’s comparative catchiness makes the song the perfect gateway drug into the Surfers’ psychedelic noise, a sound nearly as influential in Eighties underground rock circles as Sabbath was to metal.

Ozzy Osbourne has been remembered as a “pioneer,” a “fearless talent” and a “dear friend,” in an outpouring of tributes from fellow musicians and his former Black Sabbath bandmates following his death on Tuesday at the age of 76.