We’re well and truly in the nostalgia phase of the waning classic-rock period, with landmark albums celebrating 30th, 40th, even 50th anniversaries. And while many of those albums are preserved-in-amber snapshots of their angry young makers during angry young times, the Kinks spent the latter half of the 1960s decidedly out of fashion, ignoring the revolutionary climate of the day to suffuse their music with their own brand of nostalgia. It set them apart from their British Invasion peers, and they suffered on the British charts, but it gave them a sort of exoticism that puzzled and enchanted American audiences unfamiliar with the distinctly English strain of Ray Davies’ songwriting. And from this 21st-century vantage point, it gives the Kinks’ peak era—roughly 1966 through 1971, give or take—a universal appeal that has only grown over time. By ignoring the trends of the day, the Kinks and their primary songwriter, Ray Davies, ensured the longevity of their art.

The Kinks’ Arthur or the Decline and Fall of the British Empire—released in 1969, more than half a lifetime ago—is their most thematically complex album of that era, coming on the heels of The Village Green Preservation Society, a masterpiece that was all but ignored at the time of its release. Arthur, on the other hand, pivots from the cuddly whimsy of that album to the harshness of the real world, dispensing with Village Green’s songs about witches and talking cats, in favor of putting Britain under the microscope.

In some respects, Arthur is an unfinished document. The album itself stands on its own legs quite well, but it was originally intended to accompany a TV film, and the songs are tied into the plot and themes that Ray Davies had devised with writer Julian Mitchell. The story, such as it is, was inspired by members of the Davies family: Ray and younger brother Dave (the Kinks’ lead guitarist) had several significantly older sisters who helped raise them when they were small children. One of them, Rosie, married a man named Arthur, and they and their son Terry emigrated to Australia in 1964. (Rosie had already been name-checked in Face to Face’s “Rosy Won’t You Please Come Home,” and Terry in the brilliant 1967 single “Waterloo Sunset.”) Their departure was a painful experience for the Davies family—air travel was still in its infancy, international phone calls were prohibitively expensive, and the internet was not yet a glimmer in the eye of Al Gore, which made the physical separation difficult to bear—and Ray took their decision to leave home as a metaphor for the failings of Britain to provide for its own.

That overarching theme provided a tree for Ray to dangle all kinds of ideas off of, and the songs in Arthur make a sort of social history of the United Kingdom in the 20th century. Indeed, the first three songs provide a microcosm: The upbeat opener “Victoria”—still one of the best rock ’n’ roll songs ever recorded, mark it—sarcastically revels in the optimism of the Victorian era, when England was the world’s greatest superpower. Then “Yes Sir, No Sir” puts us in the boots of a combat soldier during World War I, when the elites were given cushy officer positions while the working classes were doomed to die in the trenches. And “Some Mother’s Son” is a quiet, somber anti-war song about the losses incurred in Britain’s population during the two wars.

From there, Arthur broadens its scope to sketches of post-war England, exploring happy Sundays spent with family (“Drivin’”), the top-down societal structure that separates England’s gentry from the lower classes (“She’s Bought a Hat Like Princess Marina”), and sad, sweet, simple memories of childhood (“Young and Innocent Days”). The album’s centerpiece, “Shangri-La,” is the Kinks at their very best, creating a multi-part suite unlike anything else they recorded. Its story is narratively simple yet emotionally complicated, diagramming a slice of life in dull suburbia and all of modern living’s empty promises (“Here’s your reward for working so hard/Gone are the lavatories in the back yard/Gone are the days when you dreamed of that car”). The security of standardized, middle-class living, aspired to by so many for so long, is revealed to be a breeding ground for homogeny and ignorance. And while Ray was writing from a specifically late-’60s English perspective, the frustration he explores remains universal, and it resonates today with noticeable acuity, even in this very different American culture and time.

The Arthur TV film was never finished, but the album provided the groundwork for the Kinks’ long-awaited American comeback when it was released by Reprise Records in the US. Having been banned from performing in the States in the mid-’60s, their career suffered immeasurably, but after Arthur’s release, they were finally able to return and regain a foothold, first as a cult act, and later, in the ’70s, as an arena-rock headliners. While Arthur didn’t achieve the widespread success of the Who’s Tommy—also released in 1969—it joined that album in illustrating the maturity of the long-playing record as an art form, capable of sustaining an involved narrative over its entire duration, instead of simply stringing together a band's 12 most recent songs.

The 50th anniversary edition of Arthur, released today, expands the album into a four-CD set, rehashing previous expanded editions of the album with some new material. It’s not a substitute for a proper, stand-alone copy of the album and is likely not necessary for anyone other than Kinks kompletists, but it functions as a sort of fully annotated version of Arthur that will no doubt appeal to the konverted. (And it comes with mini replicas of posters, tons of photos, reprints of articles, a metal badge, and four 7-inch singles that are reproductions of what was released at the time. It’s a kollector’s treasure trove.)

Among the box set’s two most significant supplements is the non-album single the Kinks released during this period, “Plastic Man” backed with “King Kong.” The A-side, while perfectly fine, falls in the lesser tier of singles the Kinks released during their peak, which means it’s still superior to the majority of songs by most of their contemporaries. But the B-side, “King Kong,” is a stone-cold classic, marrying the fuzz-tone guitar riffs of their breakthrough hit “You Really Got Me” with the droning of their later single “See My Friends.” It’s a heavy, spooky number that you'll still want to sing along to.

The other important bonus is the so-called Great Lost Dave Davies Album, collecting the songs the younger Davies brother had written and recorded around this time, most of them with the Kinks as his backing band. Supposedly an album was finished and presented to Reprise Records at the time of Arthur, but it was never released; I’ve always been slightly skeptical that a completed product was delivered, but at the very least, this box set recreates what might have been (supplanting an earlier disc called Hidden Treasures, released in 2011). Some of the songs were released at the time as solo Dave Davies singles or on the B-sides of Kinks 7-inches—including the best one, “Motherless Child of Motherhood,” a searing, pained exploration of a traumatic episode in Dave’s life, when he got his girlfriend pregnant when they were both 15 years old and he was forcibly separated from them both. The rest of the songs don’t quite live up to that standard, although there are some pleasant moments from Dave, including the country-influenced “Do You Wish to Be a Man” and the chummy, post-psychedelic “Lincoln Country.” Always in the shadow of his older brother, especially as a songwriter, Dave Davies’ songs don’t quite prove he was unjustly overlooked as a talent, but this collection proves his best efforts (1966’s “Death of a Clown” and 1970’s “Strangers,” which both appeared on Kinks albums) were not just lucky moonshots.

The set is completed with other stray tracks and alternate mixes, including the inferior mono album mix of Arthur (it’s simply better in stereo, unlike the majority of British LPs recorded in the ’60s), and a hodgepodge-y fourth disc that combines contemporaneous material with newer recordings from Ray. The best thing is a collage of Arthur demos, but unfortunately none are played in full; instead the disc is rounded out with a few brand-new remixes, and some songs from new theatrical pieces Ray has written that are informed by Arthur’s themes. They’re not anything you can’t live without.

“I’m constantly in an innocent, child-like state. I couldn’t write otherwise,” Ray is quoted in the set’s 68-page booklet. While that idea is easy to connect with the escapism of the songs of Village Green, it also applies to Arthur, which functions as the stark flipside of Village Green’s storybook fantasy. Arthur delves into the darker feelings of childhood, training a keen eye on the Davies extended family and their hopes, struggles, and disappointments. It’s a destabilized album, both lyrically and musically, in which jaunty British tropes like music hall and military marches are part of a continuum that includes angrier, heavier rock ’n’ roll. This idea is best exemplified by the extended jam at the end of “Australia,” a nearly seven-minute piece that sounds at times like a commercial for the Australian tourism board and at others like a ship being tossed on the waves during the long seaward journey from England to Down Under. And “Mr. Churchill Says” places air-raid sirens over another psychedelically informed instrumental.

The expanded reissue, with all its frills, only emphasizes how strong an album Arthur is in its own regard. Perhaps it’s for the best that the accompanying TV film was never finished, because, standing alone, Arthur or the Decline and Fall of the British Empire demonstrates the power of the album as a developing art form. It can be taken as a collection of 12 pop/rock songs, each of which work on their own terms. But it also tells a longer story, one that Ray’s newer recordings suggest is still in the process of being told. This journalistic ability of a full-length album was still a brand-new thing in 1969, but listening to it half a century later, it doesn’t sound like an embryonic stab at a new medium of expression—it remains a devastating, multifarious bit of storytelling. And of course, it’s still a great rock record—one of the best. Happy birthday, Arthur.