<P> John Lennon received a letter from a pupil at Quarry Bank High School, which he had attended . The writer mentioned that the English master was making his class analyse Beatles' lyrics . (Lennon wrote an answer, dated 1 September 1967, which was auctioned by Christie's of London in 1992 .) Lennon, amused that a teacher was putting so much effort into understanding the Beatles' lyrics, decided to write in his next song the most confusing lyrics that he could . </P> <P> According to author Ian MacDonald, the "model" for "I Am the Walrus" was most likely Procol Harum's "A Whiter Shade of Pale", which was a hit single during the summer of 1967 and Lennon's favourite song of the period . The lyrics came from three song ideas that Lennon had been working on, the first of which was inspired by hearing a police siren at his home in Weybridge; Lennon wrote the lines "Mis - ter cit - y police - man" to the rhythm and melody of the siren . The second idea was a short rhyme about Lennon sitting amidst his garden, while the third was a nonsense lyric about sitting on a corn flake . Unable to finish the three different songs, he combined them into one . The lyrics also included the phrase "Lucy in the sky", a reference to the Beatles' earlier song "Lucy in the Sky with Diamonds". </P> <P> The walrus refers to Lewis Carroll's poem "The Walrus and the Carpenter" (from the book Through the Looking - Glass). Lennon later expressed dismay upon belatedly realising that the walrus was a villain in the poem . </P> <P> The final piece of the song came together when Lennon's friend and former fellow member of the Quarrymen, Peter Shotton, visited, and Lennon asked him about a playground nursery rhyme they sang as children . Shotton recalled the rhyme as follows: </P>

Who sings vocals on i am the walrus