For many Beatles fans, 1967’s Sgt. Pepper’s Lonely Hearts Club Band represents the pinnacle of the Fab Four’s achievements. Densely textured, sublimely arranged and packed with some of Lennon and McCartney’s best songs, the disc remains a touchstone for every pop band that puts a premium on melody and craftsmanship. Incredibly, however, as writer Philip Norman and even Sir George Martin have pointed out, The Beatles’ psychedelic masterpiece might have been even better, had some grievous missteps not occurred.

On February 17, 1967, “Strawberry Fields Forever” and “Penny Lane” were released to the record-buying public, on what has since been described as the greatest 45-rpm record ever produced. Martin, who was complicit in the decision to issue the double-A-sided single, has since called that decision “the biggest mistake of [his] professional life.” The factors behind Martin’s regret are two-fold. First, as dictated by the customs of the day, releasing “Penny Lane” and “Strawberry Fields Forever” as a single precluded the inclusion of either song on The Beatles’ forthcoming album, which, at that time, was envisioned as a spectacularly ambitious concept disc of a different sort than Sgt. Pepper’s.

Martin later explained in The Beatles Anthology: “The only reason that ‘Strawberry Fields Forever’ and ‘Penny Lane’ didn’t go onto the new album was a feeling that if we issued a single, it shouldn’t go onto an album. That was a crazy idea, and I’m afraid I was partly responsible. It’s nonsense these days, but in those days in was an aspect that we’d try to give the public value for money. Brian [Epstein] came to me and said, ‘I must have a really great single. What have you got?’ I said, ‘Well, I’ve got three tracks – and two of them are the best tracks [Lennon and McCartney] have ever written.’ So, we put them together ….”

A second, more heartrending reason the decision was regrettable is that the concept album Lennon and McCartney had in mind would likely have been an even greater artistic triumph than Sgt. Pepper’s turned out to be. Exhausted by the madness of Beatlemania, and having therefore given up touring, The Beatles were, in Martin’s words, “generally fed up with their lives.” With two magnificent songs to serve as lynchpins, the era’s two finest songwriters envisioned crafting a collection of autobiographical songs that would take a kaleidoscopic view of their earliest memories, drawing inspiration from people and places in Liverpool that figured prominently in their childhood.

“We were in another phase of our career,” McCartney explained, in The Beatles Anthology, remarking on the sense of freedom and imagination that had taken hold in Lennon and himself. “We didn’t have to be performing every night, so instead we could be writing or chatting with our mates, or visiting an art exhibition. Having the time off gave us time to come in [to the studio] with crazy ideas. We were all opening our minds to different areas, and we [were] sharing it all with one another. There was a lot of cross-fertilization.”

Of course, in retrospect, the album The Beatles eventually did come up with wasn’t exactly shabby. McCartney’s “When I’m 64,” which was written and recorded during the sessions for the proposed “childhood” disc, became a high point of the Sgt. Pepper’s album. Furthermore, songs such as “Lucy in the Sky with Diamonds” and “A Day in the Life” were nearly on par with “Strawberry Fields Forever” and “Penny Lane,” and certainly occupied similar stylistic terrain. Still, the album suffered from weak moments, and even Lennon later concluded it was preposterous to call Sgt. Pepper’s a concept disc.

“It doesn’t go anywhere,” Lennon said. “All my contributions have absolutely nothing to do with this idea of Sgt. Pepper and his band. [The album] was not put together as it sounds, except for Sgt. Pepper introducing Billy Shears, and the so-called reprise. Every other song could have been on any other album.”

Ringo Starr concurred in that assessment, saying the overarching intent to record a “show” album got derailed. “It was going to run like a rock opera,” he said. “It had started out with a feeling that it was going to be something totally different, but we only got as far as Sgt. Pepper and Billy Shears. We thought, ‘Sod it! It’s just two tracks.’ We kept the title and the feel that it’s all connected, but in the end we didn’t actually connect all the songs up.”

Despite the disc’s flaws, Starr went to on to describe Sgt. Pepper’s as The Beatles “grandest endeavor,” not just because of the richness of the material, but also because the group was working in a spirit of supreme cooperation. Unbeknownst to Starr, however, Lennon was already mired in a quandary, having decided during the filming of How I Won the War, in 1966, that his time in The Beatles must soon end. Henceforth, until the band at last broke up in 1970, Lennon relinquished much of his leadership role in the group to McCartney.

One wonders, however, if things might have been different had Lennon and McCartney been able to follow through on the conceptual masterpiece they originally had in mind. As The Beatles’ best biographer, Philip Norman, writes in Lennon: The Life: “The premature release of ‘Strawberry Fields Forever’ and ‘Penny Lane’ took all the steam out of the Liverpool concept album idea, leaving George Martin to wonder remorsefully forevermore how great an album it might have been.”