Of course, this part of the novel isn't just set up- it's also extremely humorous. The return home of the post-incarceration Percy is laugh-out-loud funny, especially the comments from Reggie and Lord Marshmoreton. Lord M. is inclined to be astonished- and vaguely pleased- that Percy got into a fight. He has always regarded his stodgy son as scarcely human: "...you collect prayer rugs; you wear flannel next to your skin..." Of course, Lady Caroline is merely horrified that her nephew has exposed the illustrious family name to ridicule... until Percy throws Maud under the bus.
This segment also introduces us to the "downstairs" at Belpher Castle, especially the two servants who will become extremely important to the plot: Keggs the butler and Albert the pageboy. Keggs is recognizable as a Wodehousian upper servant, in the style of Jeeves. He is as aware of what is going upstairs as he is of what's happening downstairs and, cleverer than a good deal of his employers, is willing and able to manipulate circumstances to his own benefit. Albert is the type of child also familiar to readers of Wodehouse: precocious and rather terrible. Their below stairs machinations for and against their often hapless employers- and against each other- lend interest and humour to the narrative.