This was a Beatles song I discovered fairly late when the two-disc "Beatles Anthology" CD collection came out in the mid-1990's. I really enjoy the sense of fun and seeming improvization to the song--as John and Paul wrote it, it comes across as a goof-up of lounge act and maybe a bit of a parody of their earliest hits with the two-line mantra technique used in "Love Me Do" and "Please Please Me".
The Rolling Stones Brian Jones plays the alto sax on this one.
Paul later said this was one of his favorite records the group did. It grew out of John scanning a phone directory while waiting for Paul at his London townhouse. The two met up that day in 1967 to work on a song or two. The catch-phrase emblazoned on the book told users that "You Know the Name--Look Up the Number". It may be the closest The Beatles ever got to creating a Goon Show sketch or an audio version of Monty Python material. (The latter show was yet to premiere.)
This was the B-Side to the more famous "Let it Be" single. Here's some background on the recording from music critic Robert Fontenot from About.com.
The original backing track for the first section was laid down in May 1967 during work on the seminal Sgt. Pepper album, requiring 16 takes. In June of that year, fourteen additional takes produced the other three sections. (The song was also performed on January 14, 1969, during the rehearsals for the "Get Back"/Let It Be project. Vocals, however, weren't recorded until April 30, 1969, when John and Paul set aside their increasing differences and performed all the vocals in one take into the same microphone, finally completing the song for release as the b-side of the group's new single ("Let It Be," completed at the same session). Finally, John edited the song from the original 6:18 length -- which included a fifth section -- to a single-length 4:19.