This month marks the 40th anniversary of the release of Fairport Convention’s Liege and Lief. And while it is enough to pay tribute to a great and lasting album, this record thankfully gives us a little more to chew on. Liege and Lief is—and will continue to be—a curious and exciting album to look back on. Back in 1969, it wasn’t their first album, but it was the album that solidified their—and really the—British folk-rock sound, making them as influential to others as they were great in their own right. But what was new has, over the years, morphed into a classic, into its own sort of tradition. And in that way the life of Liege and Lief, and perhaps of Fairport Convention’s sound as a whole, has become cyclical.

The album is comprised mostly of reinterpretations of traditional folk songs. And they are certainly reinterpreted. They preserve the folk feel of the originals and Dave Swarbrick’s violin work—this is his first album as a full-time member—plants these songs just enough in yesterday to plug them into tradition without bogging them down. And in 1969, taking the old and refashioning it into something new, something revolutionary was a big part of what was happening in music and culture as a whole, and clearly not just in America.

But even if Fairport Convention were steeped in British folk, they owed more than an unsettling demand for something new to music on the other side of the pond. In particular, their twanged-out sinewy sound owes quite a bit to Dylan’s America, where rock and folk and blues and country come together, and when a song is either a galvanizing call or a condemnation. Simon Nicol and Richard Thompson both play a frayed and unwoven guitar on Leige and Lief, and they tangle over each other, meshing two threadbare sounds to make one sturdy and psychedelic buzz. Behind them, drummer Dave Mattacks and bassist Ashley Hutchings thump around, their rhythms steady but with a subtle intricacy, kicking up dust on every track.

And over their stringy fray, Sandy Denny belted out each song with that tumbling, rangy, and emotive voice. The traditional songs the band takes on here—again, not surprising for the time—all deal with class battles. The songs are often from the time of lords and peasants, but the stories resonated in 1969, and can sadly still resonate today. In “Matty Groves”, Denny sings of a king who battles his wife’s lover, even though he knows his wife doesn’t love him. “The Deserter” is the tragic story of a country boy thrust into war who deserts over and over again only to be caught and imprisoned—that is, until they need him to fight again. “Tamlin” turns the tables some, telling about the defiant girl Janet who catches the powerful Tamlin’s eye. She is with child, unmarried, and unabashed about it. The track stretches out into a guitar jam, with Thompson’s frenetic solos heightening the song’s tension beautifully. Each of these songs finds the poor fighting for something concrete, or at least something they know they want, while those in power often fight for little more than to stay there, or to exert their unchallenged control.

Mixed in with these traditional songs are a few originals. Opener “Come All Ye” is as fine a song as you’ll find in the band’s entire catalog. It’s a call to arms from Denny to us, the listener. She calls the fiddler, and the bass player, and the drummer, and dancers, and whoever else is around, to do their one thing, make their one contribution to the bigger sound.  If every “rolling minstrel” does their part, their noise can move the sky. It’s a bracing, and surprisingly communal way to open an album that often deals with divisions. But it once again shows how Fairport Convention were both tapping into the zeitgeist and still living firmly in tradition. The antiquated “ye” in the title alone hints not so subtly at times long gone. But the call for unity and revolution was very much a modern one, and on “Come All Ye” their demand is every much as powerful as those you’d find Dylan howling out in America.

All of these notions of revolution and change, or of twisting tradition, don’t make Liege and Lief a protest record, exactly. But it is an album that preserves the stubborn resolve of folk music, even as it threads it through amps, breaks from the tight strictures of traditional melodies, and bolsters their cry with heavy drums. The album must have sounded very new in 1969, and still sounds fresh and brilliant today. But it also feels lived in, as if it isn’t new at all to the players. As if Denny, Thompson, and company have had this sound in them all along, and had only to come together, all those rolling minstrels, to make it.

The extras that come with the Deluxe Edition of Liege and Lief are solid enough to rise above fan-only status. There are a number of the album’s songs recorded live at the BBC, and these takes—in particular the instrumental jigs and reels medley—proves the band’s sound is even heavier and more affecting live. The excellent “The Quiet Joys of Brotherhood”, given to us both live and in studio version, is a quiet, haunting number that puts Denny’s devastating vocals nicely in the spotlight. But the highlight of the extras is the band’s take on the Byrds’ “The Ballad of Easy Rider”. It’s got more of a country shuffle that anything on the album, but Thompson still crumbles notes on top of the track, and Denny tempers her wail with a beautifully restrained sadness.

Liege and Lief is hardly the only great Fairport Convention record, but it resonates more than any of the others, partly because of the universal themes and tensions it explores, but mostly because it is the height of a unique and undeniable sound. It is an album that made a genre bloom, and influenced too many bands to count—and not all of them fall into that electric folk category. But while it’s not always true that who does it first does it best, on Liege and Lief, Fairport Convention prove not just musical revolutionaries, but masters of a brilliant sound right out of the gate.