"I first saw Judas Priest at the Birmingham College of Food and Art," remembers singer Rob Halford in reference to his earliest encounter with the band he would help bring to the world stage as one of the greatest heavy metal groups ever assembled, back in their embryonic days during the late 60s/early 70s.

"I'd heard a rumor that they wanted me to come and jam. So I went to that venue and secretly snuck in and watched them and I was just mesmerized," Halford remembers in a chat with Billboard. "I think at the time the band only had three songs and they were doing all these avant-garde bluesy psychedelic progressive rock jams. Even then in its early stages you felt there was tremendous confidence being exuded by this unknown semi-professional group, and I thought, 'I wanna get in on this if I get the opportunity.' And, of course, I did." 

Nearly two generations later, the famous English outfit, whose name may or may not have come from the title of Bob Dylan's seminal "John Wesley Harding" cut "The Ballad of Frankie Lee and Judas Priest," is celebrating their impending 40th anniversary as a proper professional act with the release of "Epitaph." The vividly shot concert film documents the last stop of the quintet's final world tour at London's Hammersmith Odeon -- now known as the Hammersmith Apollo -- in May of last year. For the band, it was quite fitting to have their penultimate performance as a regularly touring act at the storied music hall, where they played at least one song off each of their fourteen studio LPs with Halford as their frontman (discounting their pair of releases with temporary replacement singer Ripper Owens in 1996 and 2000) from their enigmatic AOR-leaning 1974 debut "Rocka Rolla" on through to 2008's fiery "Nostradamus."

Perhaps made even more poignant considering, as Halford points out, the Hammersmith was the site of one of their first breakthrough gigs when they opened for British hard rock trio Budgie there 35 years ago.

"That's the way rock & roll flips and changes the story," muses the man fans lovingly call the Metal God. 

"It made sense to do the last date of the world tour in England, that's where it started as far as the music was concerned," adds guitarist Richie Faulkner, who joined Priest prior to the start of the "Epitaph" tour after longtime guitarist KK Downing announced his retirement from the business, in regards to the importance of the Hammersmith performance. "That's where we're all from, apart from [drummer] Scott [Travis, who has been with the band since 1989]. And you've got some legendary acts who've recorded there: Thin Lizzy's Live and Dangerous and Iron Maiden did 'Live After Death,' to name only two. It's such a historic venue and it just felt right, from our point of view."

For Faulkner, being thrown into the ranks of Priest to stand alongside heavyweight shredder Glenn Tipton as part of the world's foremost twin lead guitar duo wasn't as intimidating as you'd think, but he is incredibly cognizant of the fortune that's been bestowed upon his young career. 

"You're aware of the enormity of the opportunity, let's put it that way," he explains. "But you've gotta grab the bull by the horns. You've obviously been selected for a good reason and you gotta believe in yourself. And the band's been great to me as well. Me and Glenn used to get together and work out the guitar parts. We'd laugh about it quite a bit, because it's been so long since the band had played some of these songs I was showing him like 'Oh, that's wrong Glenn; this is the way it goes.' And he's like, 'Oh yeah!' (laughs) It was a fun experience."

As Priest wrap up its promotional tour in support of "Epitaph" and return to the studio to continue work on their anticipated new full-length, which they are revealing little about, Halford proclaimed that while the concert is now available on both DVD and Blu-Ray and recently aired on VH-1 Classic, nothing beat seeing it on the big screen at Manhattan's Clearview Cinema a couple of weeks before the video hit store shelves. Especially given the case that Judas Priest have yet to enjoy a proper cinematic overview of their historic career. 

"It was wonderful to go into a movie theater full of metal maniacs eating popcorn and it seemed like they all slipped a flask in because you smelled [the alcohol] going down the aisle," he laughed. "The only thing was they couldn't get the volume up to the required level because there was some other movie playing next door. As far as it being on the big screen, it was a really cool thing to do. The thing about the Epitaph DVD is that you almost have that rockumentary/documentary thing, but the music is speaking for us. It's a very direct, emotional way to convey the life of the band."