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.
She tells Jerry that the joke behind Woof, Woof, Woof is that it is a nightingale doing the dog impressions.
Midnight & Noone perform their song The Fellow with the Cello.
Gally sings the part of “the fellow on the cello”, while Susanna sings as “Susanna on piano” (pronounced “pian-ah”). The two characters are in love with each other, but both are under the impression that the other does not love them.
Vanessa is acting as stage manager for them.
Vanessa speaks to the house musicians before a performance by Midnight & Noone.
She tells them that the act do not have tab music and that Miss Midnight (Gally’s stage name) would walk off stage if tab music was played.
They protest and ask to speak to Vanessa’s mother, but Susanna shouts from the wings that they are just to deal with Vanessa.
Albert was a renowned bird impressionist as a child. However, when his voice breaks, he can no longer reach the notes needed to imitate birds like the nightingale. So that he can continue to perform, he changes to doing dog impressions instead.
Gally phones Newt to ask him to do her a “colossal” favour by filling in for her at a Midnight & Noone performance in Leeds. She tells him that he will need to play the cello, but will only have one small bit of singing in the Albert Small song.
Despite Newt’s protests, Gally insists that he must do this for her. Gally tells him that he can borrow her clothes, but he will need to buy himself a top hat. (Presumably, this is because his head would be too large for Gally’s top hat.)
Newt is worried that the audience will be disappointed if they are expecting a male impersonator but get an actual man. Gally dismisses this by saying that they will just think he is frightfully good.
Her parents are hesitant, but are somewhat reassured when Gally tells them that Susanna has recently married a Captain Noone and that he will be travelling with them.
Gally’s brother, Newt, has been on the sidelines of the discussion. When their parents withdraw to discuss the matter, Newt asks Gally more questions about Susanna’s supposed husband.
Newt deduces that Captain Noone is a ruse. He tells Gally that the play on words with ‘no-one’ is not as subtle as she might think it is.
Gally tells him that it is too late to change the name from Noone, not least because she and Susanna are planning to rename their act ‘Midnight & Noone’.
The two discuss Gally’s new stage name of Midnight, agreeing that it is better suited than Nightingale given Gally’s low voice. This gives Newt an idea for a song in which Gally would play the part of a man who impersonates birds.