It was decided by The Beatles to supply the soundtrack for their upcoming late 1967 television special "Magical Mystery Tour" and for this purpose a recording session was held on September 08 1967 with an improvisation composed by all four members originally entitled "Aerial Tour Instrumental" which was later changed to the title "Flying".
The tune is basically a bit of a blues number and on the day of the session the basic tracks consisted of George Harrison on electric guitar, John Lennon on the studio organ, Paul McCartney on bass and Ringo Starr on the drums. The entire instrumental last approximately one minute and a half and take six would be used as the backing for the master.Overdubbing for the day began with some backwards organ, the four tracks reduced to two tracks and then the melody of the song being first played by Lennon on the mellotron and the entire group joining on on vocals "La la la".
More overdubbing would later feature on the track but for now, a mono mix (RM4) was completed and the song as it stood was pressed onto an acetate at EMI. At this point, slide whistle and some flute sounds from the mellotron was featured for 30 seconds after the song ended as well as an "inboard" sound from the mellotron featuring a jazz band ending.
The song in this early form can be found on bootlegs such as the vinyl "The Lost Lennon Tapes Volume Nine" and the CD "Unsurpassed Masters Vol. 03".