“Don’t Let Me Down” is a song by the Beatles (with Billy Preston), recorded in 1969 during the Let It Be sessions. It was written by John Lennon and credited to Lennon–McCartney.
Written by Lennon as an anguished love song to Yoko Ono, Paul McCartney interpreted it as a “genuine plea”, with Lennon saying to Ono, “I’m really stepping out of line on this one. I’m really just letting my vulnerability be seen, so you must not let me down.” Lennon’s vocals work their way into screams, presaging the primal scream stylings of the following year’s John Lennon/Plastic Ono Band album.
The song is in the key of E and is in 4/4 time during the verse, chorus and bridge, but changes to 5/4 in the pick-up to the verse. It grew (like “Sun King”) from the F♯m7- E changes from Fleetwood Mac’s “Albatross” (“like she does” [F♯m7] “yes she does” [A, Am] “yes she does” [E]) with McCartney arranging instrumental and vocal parts and Harrison adding a descending two-part lead guitar accompaniment to the verse and a countermelody in the bridge. Pollack states that “the counterpoint melody played in octaves during the Alternate Verse by the bass and lead guitars is one of the more novel, unusual instrumental touches you’ll find anywhere in the Beatles catalogue.”