Bertie is sulking at home, convinced that the whole plan was a bust, when Tuppy arrives later that night. He has a black eye and tells Bertie that he's decided that he and Cora are not meant to be; he's going off to see Angela. When Jeeves gets back, he explains what happened. When Cora arrived by taxi, Jeeves was waiting for her in the foyer. He told her that Tuppy had a special request: instead of singing her planned song, he wants her to sing "Sonny Boy" for him. Cora sentimentally does so and the East End crowd unsentimentally gives her the same treatment they gave Tuppy, raining overripe fruit and veggies down upon her. Convinced that Tuppy set her up, she punches him in the eye and leaves. Bertie is, as always, in awe of Jeeves' ability to come up with a scheme- and pull it off- so quickly and successfully.
Wodehouse is as frothy and funny as usual in this Jeeves and Wooster story and, with the repeated singing of "Sunny Boy", is clearly poking fun at The Singing Fool, during which the song is sung in its entirety three times, the last two times only minutes apart. Here's that scene in the Jeeves & Wooster T.V. show from 1990 starring Hugh Laurie and Stephen Fry: