The first session took place in the control room of Studio Three from 2.30-4.45pm. Four mono mixes of When I'm Sixty-Four were made, numbered 4-7. Mix number six was intended for the US market, and seven for the UK, but neither was used. Instead a new mono mix was made on the following day, rendering all these redundant.
Also for the US market, a tape copy was made of the 22 December mono mix of Strawberry Fields Forever. In the second scheduled session, which began immediately after the first at 4.45pm and ended at 5.40pm, stereo mixes of the song were made.
The new mixes again required matching the tempos and keys of the two recorded versions, as George Martin and Geoff Emerick had done in the previous session. The first mix was of take seven, followed by one of take 26, followed by an edit of the two which was labelled remix three.
The results were deemed unsatisfactory, so a fourth mix was made of take 26. This was combined with the beginning of mix one to create a final stereo mix, numbered five.
In Studio Two between 7pm and 2.15am the following morning, Paul McCartney worked without the other Beatles on the first takes of Penny Lane. At this stage the song was known as Untitled, although McCartney had been speaking about writing a song titled Penny Lane since at least November 1965.
The recording of Penny Lane was almost as complex as for Strawberry Fields Forever. To begin with, McCartney laid down six takes of the piano backing track, and onto track two of the final attempt he added a second piano to the latter half of each verse. Track three was filled with a third piano part as well as tambourine, both of which were recorded via microphone signals fed through a Vox guitar amplifier.
The final track of the tape was filled with effects, some vari-speeded, including percussion, high two-note chords from a harmonium, and cymbals.
Work on Penny Lane continued on 30 December 1966, and into the following year.