Wishbone Ash founding guitarist Andy Powell feels a bit like a blues man most days. That’s because rock n’ roll as he and his mates knew it back in the 70s and 80s is, in many ways, an endangered art form, and it’s up to long-time devotees like Powell to keep the flame burning.

“It’s an interesting time for bands like us,” Powell told me in a recent phone interview. “There’s a heritage with certain bands that are still going strong, a history, a sort of rock attitude that defines us as music changes and society changes. The question is, ‘How will rock change with it?’ Some of what we did and said and stood for back in the day looks a bit ridiculous now, but other aspects seem kind of cool. I look to the younger audiences to keep me focused, to help me figure out how we can remain relevant. Really, it’s all about the music in the end.”

Powell has been a member of Wishbone Ash, British prog-rock powerhouse, for 47 years. He joined the band in 1969 along with fellow guitarist Ted Turner. Frontman and bassist Martin Turner and drummer Steve Upton had placed an advert in a local newspaper, hoping to find one good guitarist. However, both Powell and Turner blew the men away during auditions, and they couldn’t decide between them, so the group turned a problem into an opportunity, introducing the world of rock to an almost unheard of innovation – twin lead guitars.

What might at first blush have appeared to some as a gimmick actually helped define the trademark Wishbone Ash sound, and went on to inspire other acts (Iron Maiden and Metallica, among others) to try the same.

“It’s no easy thing,” Powell said. “What started out as a concept has become much more than that, and any innovation like that is going to have a birth and a peak to it. It has made such a solid stamp on the band at this point that you could say I’m both blessed and cursed with it. My role has been that of an ensemble player. Guys leave, new guys come in, and there’s always an adjustment period, but it works itself out and eventually our styles meld together.”

Guys leave, new guys come in. Wishbone Ash have obviously undergone a number of lineup changes since they formed in Torquay, Devon in the heady days of the British Invasion. The group that will take the stage at C2G Music Hall Monday, September 19 at 8 p.m. features Powell and Muddy Manninen on lead guitars, Joe Crabtree on drums and Bob Skeat on bass. It’s a stable lineup of veteran musicians, and one that survived a legal battle in 2013 when Powell took Martin Turner to court for touring under the moniker “Martin Turner’s Wishbone Ash.” Powell won the case, and Turner is now allowed to acknowledge that he is a founding member of the band, but not to use the band’s name in any promotional materials.

Prior to these legal wranglings and the kind of revolving members drama that plagues so many bands of such long standing, Wishbone Ash were a hungry and largely happy foursome, focusing primarily on live shows, touring with the likes of Deep Purple and honing their unique musical aesthetic, which blended elements of rock with blues, classical and folk to create the delicious sound fans clamored for, following the release of the band’s first three and most successful albums – 1970’s Wishbone Ash, 1971’s Pilgrimage and, in particular, their ground-breaking masterpiece, Argus, which dropped in 1972.

The dudes of Wishbone Ash were experiencing international fame. Argus was named album of the year by a number of outlets, and they followed that chart-topping success with Wishbone Four and two live albums, including one recorded in Memphis, Tennessee. It seemed they could go on forever as they were – Powell, Upton, and the two Turners – but then in 1973, Ted Turner exited the band, leaving a space open for a new twin lead guitarist.

Enter Laurie Wisefield, formerly of the prog-rock band Home. Powell, who has had seven guitar partners over the years, said it was making his sound mesh with that of Wisefield that proved the biggest challenge, probably because Wisefield had a sort of country rock background, whereas Powell, influenced by rhythm and blues great Albert King and blues-based rockers Jimmy Page and Jeff Beck, came of age playing in bands will full brass sections. Gradually, the two men grew used to each other’s styles, and fans could be forgiven for forgetting Wisefield wasn’t there all along.

“I’m always more concerned with the sound of the band than how great the guitar player is,” Powell told me. “It helps, of course, if you’re a great musician, but fans are more interested in the band’s overall sound, the melody, the way everything holds together. It seems to me too often guitar players now want to be the coolest, fastest new blues player on the planet. They want to be one-man shows, but that’s not what Wishbone Ash is all about. We have such a deep catalogue of classics to pay homage to, and new originals as well, and everything is geared toward that trademark sound.”

The group put out six more albums, including New England and No Smoke Without Fire, before dismissing Martin Turner in 1980. This was the end of an era, but also the beginning of the Powell-helmed Wishbone Ash that has been going strong for nearly four decades now. Wishbone Ash continues to be a constant presence on the road, and, after a summer in which they’ve enjoyed letting the fields lie fallow, they’re getting back on the bus for an 80-some city tour this fall. They’re also hard at work putting together a retrospective box set, tentatively titled The Vintage Years, which will hit shelves, airwaves and the internet later this year or early next.

Powell has for sometime served not only as Wishbone Ash’s co-lead guitar player and head band promoter, but studio producer as well, and he said he’s very much enjoyed honing the sound of Wishbone Ash’s newer releases, not to mention collecting archival material for the box set.

“Everything you do as a musician is a form of production. It comes naturally. In the end, everyone edits everyone else in the band, and ‘producer’ is a role each of us takes on in one degree or another. For me, I’ve always been keen to make sure our records build on each other, that all the releases form a kind of sound continuum. I think most musicians would tell you they could stay in the studio forever – it’s so creative and enjoyable; it’s a form of addiction. Then again, it’s great to get out and play live, too. We’re a live band, we’re known for that, and we can’t wait to see our fans’ faces again soon.”