I believe I do have a timeline of events that you might find revelatory.
In a meeting with the Soho Systems Sound Design, Jerry performs a song that he has written to be used in one of their adverts.
The song is a variation of Woof, Woof, Woof. In this version, a nightingale visits Soho Systems Sound Design to achieve the low notes she needs to do impressions of dogs.
The company express some concern over copyright because of an allusion to A Nightingale Sang in Berkeley Square at the end of the song. Hearing this, Jerry has to confess that the whole thing is based on an old Midnight & Noone song.