Where did that come from? Sgt Pepper's Lonely Hearts Club Band

The 1967 album has been called many things - from a decisive moment in the history of Western civilisation to the complete musical translation of mind-expanding drugs.

Rolling Stone magazine simply named the Beatles' Sgt Pepper's Lonely Hearts Club Band as the greatest album of all time.

A lavish concept album, Sgt Pepper's was the result of competitive drive, a lack of constraints, and the Fab Four - Paul McCartney, John Lennon, George Harrison, Ringo Starr - at the peak of their creative powers. And taking lots of drugs.

Late 1966 signalled the end of live-concerts for the Beatles, and they entered their Abbey Rd studio in London without the pressures of a schedule or a budget limit. The idea and title of the album came from McCartney, who envisioned for the group an alter-ego to shake the image of four bouncy, smiley lads with bad haircuts chased by hordes of screaming fans.

Expectations were high.

McCartney himself had declared 1966 album Pet Sounds from American rivals the Beach Boys as the greatest of all albums, and it would need something special to match it. (Pet Sounds, which was inspired by the Beatles' 1965 effort Rubber Soul, took the No 2 spot in Rolling Stone's ultimate countdown.)

Sgt Pepper's was recorded in 700 hours over 129 days. The Beatles used multi-tracking to incorporate everything they could into their concept of music: brass bands, guitar fuzz, symphonic strings, even farm animal noises.

This is epitomised in the remarkable closing track, Day in the Life, which features newspaper-inspired lyrics, a 40-piece orchestra and a ringing alarm clock, finishing on an affirming chord played by 10 hands over three pianos.

The album's aural ambition was matched by an extravagant visual cover that centred on the band in marching-band outfits, surrounded by cardboard-cutouts of their favourite and most influential figures.

Like the music, the image is an enduring trademark of the psychedelic era.

Sgt Pepper's was released in June 1967 and stories of first reaction became folklore. The Byrds' David Crosby allegedly played a tape in a Seattle hotel lobby while a hundred young fans sat quietly captivated on the stairs.

Concerns were raised about the album's connection to drugs, in particular the album's third track, Lucy in the Sky with Diamonds, a direct reference to LSD. But while these concerns faded, the praise broadened.

Said Rolling Stone in 2003: "No other pop record of that era, or since, has had such an immediate, titanic impact. This music documents the world's biggest rock band at the very height of its influence and ambition."