The Beatles left their usual surroundings of Studio Two for the smaller Studio Three for this session, which saw vocals and bass guitar overdubbed onto the rhythm track of Good Morning Good Morning.
The results of this session, which lasted from 7pm-1.45am, can be heard on 1996's Anthology 2. Following the recording of the overdubs, a reduction mix was made, with music on one track and vocals on another.
This allowed for further overdubs to be added. A mono mix was made at the end of the session, to enable George Martin to score the song for brass instruments. These were added on 13 March 1967.