IT IS a priceless insight into the creative processes of the most celebrated pop group of all time — more than 500 tapes of the Beatles arguing, singing snatches of old tunes and jamming to unreleased tracks.

But for 35 years only tantalising fragments of the missing tapes had emerged, until they turned up as evidence in an English court after a long investigation into their whereabouts. Now Beatles fans are hoping for the release of a treasure trove of material they’ve never heard before.

The story starts in 1969, in a damp room at Twickenham Studios. The Get Back sessions were an attempt to reunite the men who had dominated popular music for the past few years — to try to find a way past the tensions that were beginning to divide them, to find the sound they hoped would hark back to their first years together.

Their efforts were recorded on camera and audio reels. “We were sitting in the studio and we made it up out of thin air,” Sir Paul McCartney wrote.

The tapes recorded them performing more than 200 cover versions of work by the artists who had influenced them: Chuck Berry, Elvis Presley and Buddy Holly. They played their own version of Bob Dylan’s Blowing in the Wind, and Rod Stewart’s Maggie May. They belted out Great Balls of Fire, Hippy Hippy Shake and Lucille in spontaneous bursts of play.

The album that emerged was later shelved, then put together again a year later by Phil Spector as Let It Be.

The tapes were placed in storage. Then they disappeared. Since then, bootlegged fragments have emerged — the dialogue, arguments, jokes and songs selling for hundreds of pounds. Fans attempted to piece them together, but it was only when the tapes were advertised in a local newspaper that the investigation made any real progress.

Documents found at the home of Nigel Oliver, 55, from Slough, led investigators to raid a warehouse in the Netherlands in 2003, where the tapes were found. Police also found a key to a suitcase containing the 1960 passport of George Harrison. Three men were then called to a police station in Amsterdam. They had been the original sound engineers during the Get Back sessions. They recognised their own voices, mixed with those of the Beatles, on the tapes.

Yesterday, Oliver, who was found unfit to stand trial, was sentenced to a two-year supervision order for handling stolen goods. Neil Aspinall, the band’s first road manager and now head of the Apple estate, told the court: “These tapes have huge commercial value. There’s lots of very unknown stuff and music on there that they wouldn’t have recorded in a normal session.”

One Beatles follower has an especially personal interest. Hunter Davies, the band’s authorised biographer, said: “In 1968 Paul McCartney came to my house and he used to play the guitar on the lavatory. He found out my real first name was Eddie and wrote a song about that. Later someone sent me a bootlegged version from the sessions. It’s two verses, sort of mocking me. Now I’m hoping to hear the original.”

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