The Beatles' upcoming expanded box set of 1969's Abbey Road promises another treasure trove of previously unheard music. But with no track listing available yet, eager fans are left to guess about just what will be included on the reissue.

Will we finally get an officially released version of the medley in its intended order? George Harrison's lost guitar solo on "Here Comes the Sun"? The extended version of "Carry That Weight"? "Her Majesty" with John Lennon on slide?

Until the official news arrives, it's all conjecture. But here's a deeper look at some of the most intriguing leftovers from the sessions that produced Abbey Road.

First, note that many of these songs began their lives well before the album's main recording dates in the summer of 1969. The Beatles' initial run-throughs of "Mean Mr. Mustard" and "Polythene Pam" actually date back to the White Album demo sessions on May 29, 1968, at George Harrison's Kinfauns estate in Esher. (This version of "Mean Mr. Mustard" is notable because Lennon was still singing the original lyric about "his sister Shirley." He later changed it to "his sister Pam" so that it would link thematically with "Polythene Pam," another Lennon medley contribution.) Last year's expanded version of the White Album has already covered this era.

The Beatles then performed initial takes of a total of 12 Abbey Road songs during the Let It Be sessions in January 1969. The Anthology series already swiped some of these items, including initial passes on "She Came in Through the Bathroom Window" and "Oh! Darling" from their January 1969 work on Savile Row. As with "Oh! Darling," Anthology stitched together an edit of "Octopus's Garden," using Takes 2 and 8 from sessions held after the Beatles moved to EMI Studios in April 1969. Anthology also featured Take 5 of "Maxwell's Silver Hammer" and Take 1 of "Come Together," and included demos for "Something" (recorded on Feb. 25) and "Come and Get It" (July 24).

So, what's left? Well, a lot, actually. These 1969 sessions produced tons of early versions, extended versions and reworked versions that could provide bonus-track fodder. In some cases, certainly with "Come Together," there are other usable tries that didn't make Anthology. After all, the Beatles performed eight Studio 3 run-throughs of this album-opening track on July 21 alone.

Bootlegs have also given us sneak peeks at an alternate take of "You Never Give Me Your Money" that shifts into a jam session, a version of "Something" featuring a piano-led coda and a run-through of "I Want You (She's So Heavy)" that reportedly featured Paul McCartney on lead vocals.

The Beatles worked at Twickenham from Jan. 2-14 1969, and these recordings make up the bulk of 1970's Let It Be. But there were also multiple passes made at "Oh! Darling," "Octopus' Garden," "Sun King," "She Came in Through the Bathroom Window," "Golden Slumbers" and other songs that found a home on Abbey Road. In fact, the Beatles did five takes on "Sun King" during the first day of the Let It Be sessions, and then made several attempts at "Maxwell's Silver Hammer" and "Oh! Darling" on Jan. 3.

Their intriguing first version of "Carry That Weight," from Jan. 6, includes a bridge that never made it onto Abbey Road. Lennon later took up the slide guitar for an extended trip through "Her Majesty" on Jan. 24 that lasts more than two minutes longer than the released version.

Listen to the Beatles' 'Come Together' First Take

There were times, at this point, when the Abbey Road songs still needed more shaping. For instance, Ringo Starr's initial attempts at "Octopus's Garden" on Jan. 23 were quite skeletal, but Harrison stepped in a few days later – as seen in the Let It Be film – to help the drummer complete things. Lennon later encouraged Harrison to use place-keeper lyrics (specifically "attracts me like a cauliflower") until he got "Something" completely nailed down.

By then, the Beatles had moved back to EMI, officially setting the Let It Be project aside in May 1969 in order to focus on Abbey Road.

The medley concept probably dated to May 6, when the Beatles recorded "You Never Give Me Your Money" without a proper ending. But the order wasn't settled until very late in the process. "Her Majesty" was originally slotted to appear between "Mean Mr. Mustard" and "Polythene Pam," rather than in its now-familiar spot following "The End" and a moment of silence. McCartney decided the original sequence wasn't working, and a studio hand placed the song at the end of the tape for safe keeping. The re-edited medley flowed better for McCartney, and he decided to leave "Her Majesty" as an accidental hidden track after Abbey Road's polished conclusion. An initial orchestral crash meant to link "Her Majesty" to "Mean Mr. Mustard" remains.

Harrison returned to "Here Comes the Sun" on Aug. 6 to add some additional guitars, likely including a celebrated never-before-heard solo that was mentioned in the bonus features for Martin Scorsese's 2011 documentary George Harrison: Living In the Material World. Other song differences would admittedly be far more subtle, but perhaps still of interest to completists.

For example, the Beatles made 35 passes at "I Want You" on Feb. 22, the day it was introduced. The bulk of the released song is derived from Take 32, save for the the opening moments of Take 9 and the middle eight from Take 20. It would be interesting to hear the entirety of that principal version, if only to see if you agree with the Beatles' editing choices.

Early versions of "Golden Slumbers," recorded during the first part of July, didn't feature the familiar orchestral backing – or Lennon, who was recovering from a car accident. The strings weren't added until mid-August, when tracks like "The End" and "Here Comes the Sun" were also completed. Early takes on "Because," also recorded in August, lacked Harrison's experiments with the then-new Moog synthesizer.

Along the way, there were plenty of too-goofy attempts at still-unfinished songs, including Jan. 9's hilarious "She Came in Through the Bathroom Window" and a version of "Maxwell's Silver Hammer" where Lennon sings in an over-the-top German accent from a Jan. 10 jam after Harrison briefly quit.

The sessions also included moments that didn't make a Beatles album like "Another Day," McCartney's first solo single; "All Things Must Pass," the title track from Harrison's proper debut; "Gimme Some Truth" (which later found a home on Lennon's Imagine); and "Goodbye," a demo McCartney made for Mary Hopkin. They also cut "The Ballad of John and Yoko" and "Old Brown Shoe," a pair of non-album tracks that might provide some choice outtakes.

Inside, the expanded Abbey Road box set's booklet could give fans a fuller understanding of the signature cover art done by Iain Macmillan. The late photographer took six shots while positioned on a ladder in the middle of the street. In three of the pictures, the Beatles are walking away from the studio – an image that came to be symbolic of their looming split – while the remainder find the group heading in the opposite direction, from right to left. They cross Abbey Road in the same order each time. Macmillan's fifth photo was chosen as the featured image.



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