A George Harrison composition was ready to be recorded for the upcoming "Sgt. Pepper" project but in the end it was discarded in favour of his other composition "Within You, Without You". "Only A Northern Song" was first recorded on February 13 1967 in Studio Two at EMI in London. The recording consisted mainly of organ and percussion. The four tracks were reduced to two tracks by combining the instruments which then added George Harrison's first attempts at a vocal. The song was left to it's own devices for the moment.
On April 20 1967, The Beatles returned to the original tape with organ, percussion and vocals. A bass guitar track was added by Paul as well as glockenspiel and trumpet (played badly). The latter instruments were completed and the four track was full. Instead of a reduction, a second machine was used with a fresh four track tape and George proceeded to sing a new vocal attempt along with keyboards (piano, organ and mellotron) and tympani to produce more background screwing around notes. Since two four tracks were used, it must be remembered that the original organ/percussion take from back in February was present on both and the machines and tapes had to be successfully manually synced.
The next day on April 21 1967, the machines/tapes were synced and a mono mix was completed and given to the producers for use on the "Yellow Submarine" film project (hence it appears on that soundtrack LP). There were six attempts at the mono mix. This made a stereo mix complicated due to the syncing of the tapes and instead of trying to separate the instruments, a duophonic mix was created on October 29 1968 by boosting the high end in one channel and boosting the low end on the second channel. This fake stereo mix appears on the Apple LP/CD "Yellow Submarine" - the mono mix is available on the LP/CD of the same title in the UK only with original copies being rare. The mono mix from the film runs a semi tone lower than the commercial recording on vinyl/CD. The mono film mix can be heard on the bootleg "The Lost Pepperland Reel".
Due to the advances in technology, it is now easier to re-construct various reel tracks digitally thereby allowing the song to have true stereo mixes. The first stereo mix contains the original organ, bass and drums with the vocals from the first attempt back in February 1967 by George Harrison with slightly different words. This appears on the commercial Apple/EMI 3-LP/ 2-CD "Anthology 2". The second true stereo mix can be found on the Apple/EMI LP/CD "Yellow Submarine Songtrack" which uses the same instrumentation as the final attempt for the original LP, but remixed in true glorious stereo.