"After Gentle Giant, I went to the Dark Side," says Derek Shulman. "I became Darth Vader."

The British singer-turned-label executive is only half-serious about transforming into the Sith Lord of the music industry. But his career evolution has been suitably cinematic: starting in the mid-'60s as frontman for psychedelic R&B combo Simon Dupree & the Big Sound; then in the '70s as a co-leader of Gentle Giant, the most experimental band from prog-rock's top tier; and, over the last four decades, climbing the ranks at record labels like PolyGram, Atco and Roadrunner.

Few have experienced so much music from so many angles. After all, the guy sang lead on soul numbers, played sax on heavy-prog pieces, helped give Elton John one of his first touring gigs (as a briefly tenured piano player for Simon Dupree) and signed record deals for everyone from Bon Jovi to Slipknot. And with Gentle Giant recently issuing Unburied Treasure — a mammoth, 30-disc box set featuring their full, newly remastered catalog and 15 unheard live shows — we took the opportunity to glance back with Shulman at his unique, somewhat absurd journey.

You've never been a particularly nostalgic about your career. But there have been a lot of Gentle Giant reissues in recent years, and of course now we have this motherlode box set. Have you enjoyed looking back at all this material?

The answer is yes, believe it or not. For a long period, it was a chapter – and when you end the chapter, which is what we did in 1980, you want to move on. But at a certain point, you start to reflect. The box set, as well as some of the other things we've put together, have allowed me and everyone else to reflect on what we did and stir great memories. We also hear some of the things fans hear that become enjoyable again for us as objective and subjective observers. It's bizarre to say that. It's not really nostalgia — it's just a reflection of what was.

There's so much material here, so I can't imagine how long it took to coordinate everything. Who was responsible for finding all this stuff and spearheading the project?

It was spearheaded by a gentleman called Ian Crocket at Snapper Records. It would be great for the band to take credit, but Ian believed in what the band was about and was the one to prod us into being proactive and help find [things]. The catalog belongs to the band, and we said: "Let's go ahead and have Steven Wilson remix a couple albums that haven't been released for the box set." At the same time, we also scurried around and looked for some fo the live music we've had in various forms over the years. We did a ton of touring, but the live sets are very different from each other from the period of 1970 to 1980, and we found some very good recordings — either from radio shows or board mixes — from all over the world. Only 2,000 were pressed and put together. The people who put it together asked if they could do more, and we said no. If you say "limited," it wouldn't be fair to the fans and friends to think they were getting the short end for a money grab, which is not what we want.

Watch a Trailer for Gentle Giant's 'Unburied Treasure'

Was the band involved in tracking down all of the tapes and memorabilia?

It's funny — when you're in a band, you stash things away in closets, like a ticket or a tape. He jousted us to find whatever we had stashed away somewhere. [Gentle Giant guitarist] Gary Green had a ton of memorabilia. Every year there's a convention called GORGG [Global On-Reflection Giant Gathering], and for whatever reason he kept a lot of memorabilia from gigs. He had a lot of stuff that no one had seen. He was a great point of reference, but we all found pieces of different memorabilia from our past. We listened to them or looked at them, and decided with Ian what should be in there.

Going back to the beginning: Roy Thomas Baker, best-known for producing Queen in the early days, helped engineer the first Gentle Giant album in 1970. What do you recall about working with him?

He was Roy "Get the Tea" Baker: "Roy, can you get the tea?" He was the tape-op at Trident Studios, and Tony Visconti was the producer. Roy was an upcoming guy at Trident, and he subsequently made his name as a big producer. This is a period when everyone in the classic-rock world knew each other. We were all coming through in different fashions, so we were all friends for many years. At the same time we made our first album with Tony, we'd do our session and then [David] Bowie would come in, and we'd hang out with him; at the same time, Tony was working with T. Rex. Queen would walk in on the other side.

At that point in England, it was a superb time. Everyone was coming through in their fashions. It was a great time to be in a band and be a musician, the late '60s, early '70s — we all knew each other and what was going on and were supportive as friends. You'd do your sessions, hang out and see another big band doing their session. Everyone was in it together, in both musicians terms as well as producers and tape-ops and engineers.

Listen to Gentle Giant Perform 'Funny Ways'

Speaking of Gentle Giant's debut, you recently mentioned that a collector found the tapes for the first album, which have been remastered for the new box set. Are you planning a separate reissue of that LP?

The album is gonna be in the box set, but we're planning to put some vinyl out for the first four albums, which I don't think has been done for a very long time. We have the actual masters, and we're gonna put that out in the first quarter, and we'll go from there. You're the first person to hear this!

Obviously, Gentle Giant compositions took time to work out as a band. You can't just show up in the room and have something like "Knots" figured out in 20 minutes. Do you recall any songs that were a particular struggle to put together?

Every piece was a struggle. We loved to challenge ourselves. That was a very important point for the band. We worked very hard in rehearsals and in composing to challenge ourselves and each other to do things we didn't think we'd be able to do. It was a struggle, of course, but a pleasant one we could overcome and learn from each other. At the same time, onstage, when we presented ourselves in a way we had fun with — rather than sort of like looking down at our instruments and not showing the audience that we enjoyed our music. We wanted to see smiles on our fans' faces, rather than quizzical looks and people looking at the instruments.

Listen to Gentle Giant Perform 'Knots'

The band has always had this reputation as being super serious, but most Gentle Giant songs are really fun and often playful.

We didn't take ourselves seriously. We took our music seriously.

I often marvel watching Gentle Giant live clips — the amount of symmetry and coordination that went into playing pieces of this magnitude. One slip-up with songs like these and you're screwed. How often did you guys get out of sync or make a mistake that derailed a song?

People would make mistakes onstage. I'd forget a line or two in a song, and I'd ad-lib, and no one would notice. There were out-of-tune vocals, mistakes on the keyboard or guitar. In general terms, there weren't many slip-ups onstage because we worked very, very hard to make sure we were coordinated. Onstage, there were elongated versions. The albums were sketches for the painting that was presented [live]. The painting was much more fun and illustrated what the band was about, rather than the sketch on the album. But there were a couple shows that stick in our memory as being pretty grim.

Obviously, one which is well-known and a joke in certain respects was the first tour we did in North America with Black Sabbath, at the Hollywood Bowl [in 1972]. First of all, Gentle Giant and Black Sabbath as a bill is almost like an anathema: salt and pepper, chalk and cheese, as it were. But what we did on that tour was learn: When we went onstage, no one really knew Gentle Giant, maybe a smattering of people, but we were able to win them over through sheer willpower. When we'd finish the shows through North America, we got a good ovation. But at the L.A. Forum, we'd change into softer music with a violin and cello, which fans of Black Sabbath had never seen or heard. During the song "Funny Ways," someone threw a cherry comb onstage, and it exploded in front of me and my brother Phil. We got very upset and cursed the audience out. And the boo that went up was spectacular. There was a hilarious "get out" and this, that and the other. I don't think you could imagine how negative our attitude toward the audience was. We finished our set in a hurry and got the hell out of L.A.

Listen to Gentle Giant Opening for Black Sabbath

Did you get to know the Sabbath guys very well?

Yeah, we had the same management, so we were very familiar with the band. They were good friends actually, but they were going through a stage in their career where they were imbibing a little too much, shall we say, their own chemical romance. In fact, on that same show, I was at the side of the stage when Tony Iommi had done a little too much and collapsed literally on his face and his guitar was feeding back, and the audience was going crazy, thinking it was part of the set. But he didn't actually get up. It was pretty amazing that we got through that. But as far as musicians getting along, of course we did. We were great friends. It wasn't the best pairing, but as far as friendship is concerned, we knew those guys for many years and still do, actually.

You also toured with Yes around that time. What was your experience with them?

At that time, they were riding an enormous wave, and we were just coming up. I think — how can I put this? — they were a little suspect of our being very good, and they were a little nervous about putting us out there. We did very well on that tour, and I think they were less than friendly to us, although they weren't unfriendly. As the tour went on, the lights that were part of our stage show were pulled, and their drum kit went forward a little further. They were concerned that we were doing too well, but nevertheless, it was a good tour. I knew those guys back in the day, have known them ever since and have done work with them. But the memories weren't bad. Yes were great then. During the Fragile/Close to the Edge period, they were superb as a band.

Listen Gentle Giant Perform 'The Advent of Panurge'

One thing people forget about — or maybe missed the first time around — is how funky Gentle Giant was. How many prog bands can you describe that way? John Weather's drum tracks are often anchored in a straightforward groove, which was the perfect launching pad for the dense parts over top. You all had an R&B background. Do you think that played a part? And is that something you always tried to maintain?

Yeah, I agree with you. John was and is a spectacular drummer. He's someone who grooved; he was a great rock drummer with influences from R&B. But his groove and rhythm was perfect, and perfect for the band to lay fiddly-fiddly stuff on top. People say "progressive," but I think we were more than a rock band than whatever "progressive" meant — a rock band who did things in a quirky way. But certainly R&B and groove and soul were part of the band, and we never got away from that, even though people said we were Old English and "medieval" and jazz or whatever. But groove was absolutely important for us, and John was the anchor for that – absolutely, 100 percent. And he hit the snare so damn hard that my hair in the back would part in the middle. He was a heavy, loud drummer — really one of the best, most unsung drummers in the business.

If I had to pick one song that defines Gentle Giant in my mind, it would be "The Advent of Panurge" from 1972's Octopus — maybe because that's the song that got me into the band. But I had to ask you about it. Do you remember much about writing or recording that song?

Lyrically, Phil [Shulman] was still in the band, and we were putting together the giant theme from French writer Rabelais and Gargantua and Pantagruel. As far as the music was concerned, [keyboardist Kerry Minnear] came up with the first part of it, and then we went into some heavy stuff, which Ray [Shulman] and I put together. We integrated both, but I think we did it pretty seamlessly. That's one thing we tried to do: heavy and soft, gentle and giant, together in a seamless way. The thing we really enjoyed was surprise: We didn't want to have people sit in their hands and know what's coming next, or have pretentious keyboard parts that tried to be like a symphony orchestra. We wanted to keep people on their feet.