On his 1974 album, Past, Present and Future, British folk-pop troubadour Al Stewart recorded “Nostradamus”, a nine-minute opus detailing the predictions of the 16th-century prophet. It told of the visions in which Nostradamus reputedly foresaw such world events as the rise of Hitler and Great Fire of London, and was delivered with Stewart’s nasal voice and some gently swaying acoustic guitars.

Judas Priest must have fuckin’ hated it.

On its new double-disc, Nostradamus, the British metal legends offer up their own biography of the French seer, with operatic screaming and gonzo guitars. As lead vocalist Rob Halford explains from his home in Birmingham, England, where he’s taking a few days off before a world tour kicks off in Helsinki, the idea for the album came about through the group’s manager, Bill Curbishley.

“We’ve been wanting to do a concept record since we’ve been together,” explains Halford, “and when he said Nostradamus we went, ‘Ooof, thanks Bill. We waited 30 years for that moment.’ But it’s been a joy to make. We tried to cover his life with our style of metal, tell everything about the man, from his prophecies to the real-life conditions that he went through. You’ve got an hour and 40 minutes of this incredible journey, and it’s like a movie, you know. You can put the speakers up, close your eyes, and get lost in the world of Nostradamus.”

Halford departed the Priesthood in 1993—and spent 10 years covering more adult and political themes in the metal acts Fight, Two, and Halford—before rejoining in time for the release of 2003’s Metalogy boxed set. He’s happy as hell to be back, and touring any place where you’ll find people willing to make the devil-horn sign and scream “Judas fucking Priest!” at the top of their lungs. As the metal god himself so happily proclaims, that’s basically everywhere, except maybe Vatican City.

“We’ll be roaring around the world until Christmastime,” Halford points out, “and that’s because Priest is loved all over the planet. Once we say we’re goin’ on the road, everybody wants to see us, from the U.K., all over Europe, North American, South America, Australia, Japan, New Zealand, Korea.”

Without Nostradamus around to offer tips, it’s hard to foresee how the new Judas Priest CD will be embraced by the band’s worldwide following. While the Priest fan of today has, hopefully, advanced from the type of waste-case portrayed in the 1986 documentary Heavy Metal Parking Lot, there’s a chance he or she is more interested in “Living After Midnight” and “Breaking the Law” than contemplating the ancient prophecies of some dude from France.

Musically, the sprawling Nostradamus is the band’s most diverse album yet, and for every trademark guitar duel between K. K. Downing and Glenn Tipton there’s an atmospheric passage featuring the anti-metal instrument known as keyboards.

Whether or not Nostradamus puts his band back at the top of the heavy-metal heap, one thing is perfectly clear to Halford: there’s never been a better time to be immersed in the genre. “I’ve got a copy of Kerrang! in my lap at the moment,” he says, referring to the influential British metal mag, “and it’s just full of all these different bands. You know, when I was a kid growing up, there was nothing like this in terms of diversity, and now it’s just incredible to be a metalhead in 2008.”

Halford’s ravings about the current state of metal are supported by the recent success of fellow Brit ear-busters Iron Maiden. Since reuniting with original vocalist Bruce Dickinson and setting off on its latest tour, Maiden has been selling out arenas and stadiums everywhere.

When asked if there’s any competition between the two acts to win over 21st-century headbangers, Halford takes a diplomatic approach. “There’s always been a tremendous feeling that we’re all doin’ the same thing as far as taking our British metal all over the planet,” he proclaims. “And the roots of metal are where I’m talking to you from today, in the Midlands [of England]. This is where it all started, with Priest and Sabbath. And then, of course, the new wave of heavy metal started in the ’80s, with bands like Maiden and so on. So we’re all flyin’ the flag, so to speak. We’re all going strong, and things are fantastic.”

Everything may be hunky-dory for Halford and his leather-clad mates these days, but it wasn’t always that way. Judas Priest has had to deal with a fair amount of adversity in its 34-year recording career, particularly when it was sued in a 1990 civil action after two young Reno men shot themselves and a Nevada attorney tried to pin their actions on a “subliminal” message on the 1978 Priest track “Better by You, Better Than Me”, actually a cover of a 1969 song by British rock band Spooky Tooth.

“My Chemical Romance just went through it recently,” Halford explains. “Some kid took their life, and I guess the lawyers or somebody wanted to find somebody to blame. Again, we refute that a thousand percent; prove to us that music can take your life. It can’t. In fact, it’s just the opposite. Music has been a wonderful source of support and creativity, and great things have happened since music was invented.”

Speaking of inventions, Halford would neither confirm nor deny the rumour that Priest’s next project would be a three-disc opus on the life and times of Leonardo da Vinci.

Judas Priest plays GM Place next Thursday (July 24).