Penny Lane was almost complete prior to this session, but required some additional overdubs by session musicians.
The session began at 7pm and ended at 1.45am the following morning. Four flutes and two trumpets were added, after which two mono mixes were made.
The flautists were Ray Swinfield, P Goody, Manny Winters and Dennis Walton, while the trumpeters were Leon Calvert and Freddy Clayton. As they rehearsed their score with George Martin and Paul McCartney, John Lennon was in the studio control room recording the proceedings, using vast amounts of tape echo and varispeed.
The rehearsal tape began with 90 seconds of warm-ups and discussions, after which Martin called for a 10-minute break. McCartney played through Penny Lane on a piano, telling the musicians that "it's kinda confusing to what key it's in". He also sang some suggestions for the brass parts.
Martin then conducted the flutes in a rehearsal of the chorus, and were joined by the trumpets in a second attempt. The song was played back twice, and Martin can be heard complaining that something was out of tune.
Lennon took the rehearsal tape home at the end of the session. The recordings subsequently appeared on bootleg recordings, although no copy exists in the EMI vaults.
The musicians' parts were eventually added to track three of the four-track tape. After they were completed to everyone's satisfaction, two rough mono mixes, numbered five and six, were made.