April 1967. Having just finished work on Sgt. Pepper, all four members of the Beatles drove from Abbey Road to Mama Cass’s flat in Chelsea. In the early hours of the morning, they turned the speakers outwards and played their latest creation at full volume. The Beatles’ confidant Neil Aspinall remembers that, far from being annoyed, the neighbours knew exactly what they were hearing. “All the windows around us opened and people leant out . . . It was obvious who it was on the record. Nobody complained. A lovely spring morning . . .”

Encapsulated in this idyllic recollection is the reason we can’t let go of Sgt. Pepper and what it represents. It was an album that had an immediate impact on the world around it. You heard these songs and, somehow, things could never be the same again.

Within two years, contemporaries such as the Rolling Stones (Their Satanic Majesties Request), the Bee Gees (Odessa), the Zombies (Odessey and Oracle) had all attempted to make their own Peppers: kaleidoscopic, ambitious pop records boasting a central thematic conceit). On hearing Pepper, Brian Wilson aborted work on the Beach Boys’ Smile.

In the ensuing decades, music has become ubiquitous and so much more fragmented that it’s hard to imagine such a scenario ever happening again. And yet, it’s something we desperately want to happen. Wasn’t it the desire to believe that Oasis had just made their Pepper that made critics lavish Be Here Now with praise? But if you go back to Sgt. Pepper now and listen once more, what sets it apart is that the songs are not burdened with a sense of their own importance. A lot of “important” albums take place on such rarefied emotional territory that there never seems to be a good time actually to play them.

Sgt. Pepper, however, is no worse an album you when you’re washing up to it at 10am than when you’re getting stoned to it at 3am. The “vaudeville” elements to which William Mann, who reviewed the album for The Times, referred provide a certain amount of emotional relief from A Day in the Life and She’s Leaving Home. At the same time, the passing of the decades confers extra poignancy upon certain moments. Just as the passing of time has turned Penny Lane (originally recorded for inclusion on Pepper) into a snapshot of a world to which we can never return, you can’t hear When I’m 64 without thinking of the travails endured by its writer in the past ten years.

McCartney had the popular touch, but (until John Lennon intensified his friendship with Yoko Ono) he was also the avant-gardist in the Beatles – and Sgt. Pepperis where you’ll find most of the evidence. On A Day in the Life, it was McCartney who orchestrated possibly the most famous single sustained chord of the past century by instructing an orchestra to go from their lowest to highest notes over the course of a 24-bar “freak out”. John Lennon’s contribution here, of course, is not to be underestimated. McCartney may have originally conceived Pepper as a response to the Beach Boys’ Pet Sounds; LSD prompted in Lennon something much closer to the childlike fantasia that had propelled Brian Wilson. Lucy in the Sky with Diamondsand the ghostly boom-thump Victoriana of Being for the Benefit of Mr Kite! rank among Lennon’s absolute best.

All of which is surely enough to confirm Sgt. Pepper as the Beatles’ (and indeed pop’s) creative high watermark? Twenty years ago it was a matter on which there was some critical anonymity. But changing times have resulted in a significant change of hardware; there’s a whole generation whose only experience of Sgt. Pepper is on CD. And vinyl best obscures the primitive technology with which George Martin had to work; deny Sgt. Pepper the unforgiving sonic clarity of CD and the saucer-eyed hyperreality of the original returns: the rush-hour clatter of Good Morning Good Morning; Ringo’s drum fills on A Day in the Life; the kitchen-sink flourishes of She’s Leaving Home.

So, as long as you have access to the record’s black plastic incarnation, Sgt. Pepper scrubs up as well as ever. If any band today came up with such a wealth of inspired songs, the shock of their achievement, combined with the critical scrutiny and subsequent expectations, would send them into creative paralysis. But as the first footprints to tread the pop-cultural snow-fall of the 1960s, the Beatles didn’t know about all of that. Instead, two weeks after Sgt. Pepper’s arrival, they started work on All You Need Is Love. Two weeks. How cool is that?

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