Britomart announces Undershaft's imminent visit to the stupefied party. Barbara is amused and expectant: after all, her father has a soul to be saved like everyone else. Lomax blathers nervously. With sarcastic suavity, Britomart asks Cusins to translate Lomax's "vulgar" street dialect. She warns the children to be on their best behavior.
Major Barbara begins with a comic meeting between an aristocratic mother and her only son. Though Lady Britomart ostensibly invites her son to take charge of the family affairs, she has already made arrangements for Undershaft to come to the house and resolve them. Note how, as with her largely uncontrollable daughters, Britomart chastises Stephen for fidgeting, warns him against being on his best behavior, and displays other maternal behavior. Lady Britomart appears as the overbearing mother of a fatherless household.
As such a maternal figure, Britomart will figure in the play as the bearer of an increasingly antiquated sense of convention and familial loyalty. She is sympathetic in being the play's great lady: charming, witty, and aristocratically provincial in her perspective on the work. Hopelessly she will insist on propriety in a family not particularly invested in such social forms.
Here Britomart's insistence on propriety emerges most clearly in her disparagement of Lomax. As in many of Shaw's works, dialect figures as an especially vexed point of contention in the household. Largely deployed for comic relief, Lomax's speech is a caricature of the society man's English. A frivolous playboy, he spends much of the play delivering stunted and tactless exclamations. Lomax converses in what Britomart considers "schoolboy drivel," a "vulgar" street dialect that says little and requires translation into proper speech. It behooves the reader to follow these clashes over dialect closely. The importance of the difference between proper and improper English in the play will become clearer in Act II, when dialect raises a number of questions regarding class difference.
As we might expect, Lady Britomart objects to her ex-husband for his betrayals of convention, familial duty, and morality, having divorced him for his disinheiritance of Andrew. Prefiguring the elaboration of what Shaw terms Undershaft's "gospel," Britomart bemoans his "religion of wrongness" and his insistence on always living in an "unashamed" fashion. As her only response to the new system of morality Undershaft introduces is to turn away in disapprobation, her family will ultimately abandon her upon his return. Stephen will assert his majority and cast aside her to discuss his future with Undershaft alone. As we will see, though she may play the great lady, she cannot compete with a father who compels those around him as a great man.
A formerly tabooed subject of conversation in the household, Undershaft already appears here as a compelling, all-powerful father—a man who, in holding Europe under his thumbs and determines law, can in no sense hyperbolically liken himself to the Roman Emperor. As if Andrew's name were not enough, his son's exclamations make his phallic prowess rather explicit: "The Undershaft torpedo! The Undershaft quick firers! The Undershaft ten inch!" The father's almost pornographic name bears his power, referring to how his firm serves as Europe's foundation (or "under-shaft"). Moreover, as Britomart reveals, Undershaft has served as the provider for their family all along as well. Thus he already holds them in his power.