Its famous lyrics with phrases such as "I am the eggman" and "Sitting on a cornflake waiting for the van to come" have been analysed many times over the years but no one has ever been completely certain what Lennon meant.
Most believe the words were inspired by the Lewis Carroll poem The Walrus and the Carpenter but Lennon himself gave numerous interpretations.
In Ian MacDonald's definitive book on The Beatles, Revolution in the Head, the author said the song was an angry sequel to the darkly melancholic "Strawberry Fields Forever" and became Lennon's ultimate anti-establishment rant.
"A trace of the more philosophical Lennon remains in the song's opening line ["I am he, as you are he, as you are me, and we are all together"] but the rest of the song is pure invective, including a swipe at the mantra- chanting of the Hare Krishna movement to which George Harrison was inclined."
Lennon frequently bragged that he wrote songs while under the influence of LSD, and the lyrics contain the line "See how they fly, like Lucy in the Sky" - a reference to his earlier classic "Lucy in the Sky with Diamonds". Others claimed that the phrases "stupid Bloody Tuesday" and "waiting for the van to come" referred to a widely circulated rumour that Paul McCartney had been killed in an accident. Lennon's later song "Glass Onion" revealed that "The Walrus" was McCartney himself.
The "Walrus" lyrics were bought by a fan six years ago for pounds 40,000 and will be sold on 30 September at Christie's in South Kensington. One possible bidder could be Noel Gallagher of Oasis, who already has a collection of Beatles memorabilia.
A spokeswoman for Christie's said: "These are working lyrics of Lennon's trademark song. It is one of the most interesting examples of lyrics to come on the market."
The previous record for Beatles memorabilia was a notebook written by their road manager, Mal Evans, which included McCartney's lyrics for "Hey Jude". It fetched pounds 111,000.