Today saw the first Beatles-related activity at EMI/Abbey Road Studios since June. Says The Beatles Bible,
After Brian Epstein told EMI that The Beatles would not be making any new music available for the Christmas market, the record company chose to prepare the first UK compilation of their music.
The record was to be called A Collection of Beatles Oldies and released in both mono and stereo versions. This necessitated remixing in stereo any songs that currently existed only in mono, such as “Paperback Writer,” which George Martin and crew worked on today.
None of the actual Beatles were around, of course. They were probably trick-or-treating dressed as the Stones.