The Beatles were absent from the recording Studio for approximately two months and picked up in late August to start their soundtrack titles for the upcoming television film "Magical Mystery Tour" of which the title track was completed.
On August 22 1967 The Beatles entered Chappell Recording Studios in London to begin a Paul McCartney composition entitled "Your Mother Should Know". In order to complete the basic track, Paul played the piano and Ringo played drums with a double lead vocal from Paul. At this stage, only two Beatles were featured and take 8 was considered as "best". An acetate of the song must have been made at this point. This take was used during the production of the film.
You can hear the results of this basic track on such bootlegs as the vinyl LP "Not For Sale" as well as the vinyl box set "Golden Slumbers". It's also heard on the bootleg CD "Acetates". I've tried to find a youtube equivalent but could not.
The next day on August 23 1967, the drums and piano were combined onto one track and the double lead vocal was also combined onto a second track to allow for two tracks of backing vocals and a bit of guitar in the choruses. The song was left in this state for the time being.