"It's like an avalanche of guitars, isn't it?" Jimmy Page says of this early draft of Immigrant Song, the opening track of Led Zeppelin III. The album, he says, "had to have an introduction to it, not because we were trying to chase Whole Lotta Love, but to have this real hypnotic riff going, and this bloodcurdling scream of Robert – I thought, 'That's the way to open an album.'"  Now you can hear that unreleased version of Immigrant Song, from the companion disc to the remastered version of Led Zeppelin III, to be released on 2 June on Atlantic/Swansong. At this distance, memories are unsure – Page isn't certain whether it's Robert Plant's final vocal, and "I'm not convinced that's the final bass on it. But it's a work in progress – the guitars come in, cutting across."  Immigrant Song was a tune Page had composed before the main writing on III began, and Plant's lyrics came after the band played in Iceland as part of a cultural exchange, and he became fascinated by Viking mythology. "I was always a history buff and I really went, 'Wow! These guys came from here to Stranraer?' You know: 'What was going on?' It's something to sing about which was good.  "You can’t be anything else but moved by the place. I saw those huge boats, I went to museums in Denmark and Norway, and saw the boats that they dug up, and I thought: 'Wow, these guys were really on a mission. What did they bring with them?' They brought loads and loads of very very interesting social and artistic phenomena."  And Page's riff? "The actual soundtrack of it is stunning – the song is spectacular."  Zeppelin's visit to Iceland, despite being just for a few days, is still remembered. "I’ve been back a couple of times since," Plant says. "I met the prime minister once and he said: ‘I was in that room!’"  Immigrant Song is that rare thing: a song that on different listens appears to belong to different members of the band. Sometimes it's all about Plant's unearthly wail and wonderfully preposterous lyric: "The hammer of the gods will drive our ships to new lands/ To fight the horde, singing and crying: Valhalla, I am coming!" Sometimes it's Page's viciously slashing guitar that comes to the fore. At others it's John Paul Jones's bass, racing up the neck during the "On we sweep …" section, with a funkiness that's incredible given that this is fabulously heavy music. And sometimes it's all about John Bonham's drums, which sound as if they really are being hit with Thor's hammer. It's still a visceral experience, a heart-racing piece of rock music.  Have a listen to the early version and let us know what you think (and you can read an extended piece about the making of Led Zeppelin III here next week).
In our latest instalment from the Zep reissues programme, we've got an early version of one of the classics – and read how Jimmy Page and Robert Plant put it together