The song was largely written during a recording session at
EMI Studios on 18 September 1968 by
John Lennon and
Paul McCartney. McCartney: "We thought, 'Why not make something up?' So we got a riff going and arranged it around this riff. So that is 50–50 John and me, made up on the spot and recorded all in the same evening." During the session, the Beatles and the recording crew made a short trip around the corner to McCartney's house to watch the 1956 rock & roll movie ''
The Girl Can't Help It'' which was being shown for the first time on British television. After the movie they returned to record "Birthday".
George Martin was away so his assistant
Chris Thomas produced the session. His memory is that the song was mostly McCartney's: "Paul was the first one in, and he was playing the 'Birthday' riff. Eventually the others arrived, by which time Paul had literally written the song, right there in the studio." Everyone in the studio sang in the chorus and it was 5 am by the time the final
mono mix was completed. Lennon said in his
Playboy interview in 1980: Birthday' was written in the studio. Just made up on the spot. I think Paul wanted to write a song like '
Happy Birthday Baby', the old fifties hit. But it was sort of made up in the studio. It was a piece of garbage." "Birthday" begins with an intro drum fill, then moves directly into a
blues progression in A (in the form of a guitar riff doubled by the bass) with McCartney singing at the top of his
chest voice with Lennon on a lower
harmony. After this section, a drum break lasting eight measures brings the song into the middle section, which rests entirely on the
dominant. A repeat of the blues progression/guitar riff instrumental section, augmented by piano brings the song into a
bridge before returning to a repeat of the first vocal section, this time with the piano accompaniment. ==Legacy==