It's not pleasant for me, either, especially if you are still so childish that you must make it worse by a display of embarrassment. It is only in the middle classes, Stephen, that people get into a state of dumb helpless horror when they find that there are wicked people in the world. In our class, we have to decide what is to be done with wicked people; and nothing should disturb our self-possession. Now ask your question properly. (1.53)
Lady Brit becomes annoyed with Stephen when he gets tongue-tied at his mistaken impression that his father had a child out of wedlock. She turns the moment into an opportunity to lecture Stephen on behaviors and attitudes that are appropriate for his class, as opposed to what would be okay among the "middle classes."
Oh yes: they married just as your father did; and they were rich enough to buy land for their own children and leave them well provided for. But they always adopted and trained some foundling to succeed them in the business; and of course they always quarrelled with their wives furiously over it. Your father was adopted in that way; and he pretends to consider himself bound to keep up the tradition and adopt somebody to leave the business to. Of course I was not going to stand that. There may have been some reason for it when the Undershafts could only marry women in their own class, whose sons were not fit to govern great estates. But there could be no excuse for passing over my son. (1.61)
Here, Lady B makes a curious statement about her own class: Apparently the women in it have historically not necessarily produced men with the character necessary to be lords of the land—Lady B being a very notable exception, we're sure. Anyway, Andrew insists on continuing the tradition of giving a foundling the opportunity to be the fabulously wealthy overlord of the Undershaft fortune . . .
I'll tell you why. Fust: I'm intelligent—ff ff f! it's rotten cold here [he dances a step or two]--yes: intelligent beyond the station o life into which it has pleased the capitalists to call me; and they don't like a man that sees through em. Second, an intelligent bein needs a doo share of appiness; so I drink somethink cruel when I get the chawnce. Third, I stand by my class and do as little as I can so's to leave arf the job for me fellow workers. Fourth, I'm fly enough to know wots inside the law and wots outside it; and inside it I do as the capitalists do: pinch wot I can lay me ands on. In a proper state of society I am sober, industrious and honest: in Rome, so to speak, I do as the Romans do. Wots the consequence? When trade is bad—and it's rotten bad just now—and the employers az to sack arf their men, they generally start on me. (2.8)
Snobby Price is explaining his present circumstances to Rummy. Basically, he seems himself as a victim of class—and his own superior intelligence, which makes his capitalist overlords prickly with him and less likely to keep him employed. This sounds kind of like those kids who claim they would be getting straight As, except they're super bored in class, doesn't it?
That is the general opinion of our governing classes. The novelty is in hearing any man confess it. (2.230)
Here, Dolly is appreciating that Undershaft doesn't try to dress up the dominant attitude among the "governing classes" that money and weapons rule the roost and are solely responsible for getting things done.
LADY BRITOMART: In good society in England, Charles, men drivel at all ages by repeating silly formulas with an air of wisdom. Schoolboys make their own formulas out of slang, like you. When they reach your age, and get political private secretaryships and things of that sort, they drop slang and get their formulas out of The Spectator or The Times. You had better confine yourself to The Times. You will find that there is a certain amount of tosh about The Times; but at least its language is reputable. LOMAX [overwhelmed]: You are so awfully strong-minded, Lady Brit— LADY BRITOMART: Rubbish! […] (3.49-51)
With her typically ironclad vision of what constitutes right and wrong, Lady B is lecturing Charles on how to act in a way that meshes with his class position. Like Barbara, he has a tendency to talk in a way that she finds, shall we say, unbecoming given his birth and breeding.
Just as much as it is your duty to submit to your husband. Come, Biddy! these tricks of the governing class are of no use with me. I am one of the governing class myself; and it is waste of time giving tracts to a missionary. I have the power in this matter; and I am not to be humbugged into using it for your purposes. (3.91)
While Lady B is pretty successful in correcting Charles and Barbara's behavior with her forceful reminders of their class, Andrew is immune to it; he's going to do what he wants to do, regardless of her attempts to get him to do his class-determined duty to leave the business to his son.
LADY BRITOMART: What do you mean by the horrible truth, pray? CUSINS: That she was enormously rich; that her grandfather was an earl; that her father was the Prince of Darkness— UNDERSHAFT: Chut! CUSINS:—and that I was only an adventurer trying to catch a rich wife, then I stooped to deceive her about my birth. (3.247-250)
We are learning a deep, dark secret about Dolly here: When he first met Barbara at the Army, he didn't know she was upper class and rich, so he actually thought that he would be a catch for her. When he found out the truth, he realized that that he was the potential opportunist here.
Don't listen to his metaphysics, Barbara. The place is driven by the most rascally part of society, the money hunters, the pleasure hunters, the military promotion hunters; and he is their slave. (3.301)
Dolly is giving his opinion of Undershaft's place in society (and his factory's). However, he actually reverses the general impression that Undershaft is Mr. Powerful, envisioning him as a "slave" to this "rascally" element.
There is no wicked side: life is all one. And I never wanted to shirk my share in whatever evil must be endured, whether it be sin or suffering. I wish I could cure you of middle-class ideas, Dolly. (3.418)
Barbara has always maintained that there's no such thing as "good" and "bad" men, since they're all children of God, and her points here agree with that general view point. Apparently, in her view, thinking that there is a "wicked" side of life that can be kept separate from the rest of life is "middle class." Hmm, maybe she is a bit of a snob after all?
That is why I have no class, Dolly: I come straight out of the heart of the whole people. If I were middle-class I should turn my back on my father's business; and we should both live in an artistic drawing room, with you reading the reviews in one corner, and I in the other at the piano, playing Schumann: both very superior persons, and neither of us a bit of use. Sooner than that, I would sweep out the guncotton shed, or be one of Bodger's barmaids. Do you know what would have happened if you had refused papa's offer? (3.420)
Barbara has finally come around to her mother's view that she must act in a way that matches her class position. However, in defiance of her mother's values, she's using that realization to justify being okay with her dad's business (and the fact that Dolly is joining it).