In Act III of Oscar Wilde's satire of English Victorian customs, the character Lady Bracknell, whose demeanor and attitudes towards the social status of others define the play, is shocked to learn upon entering the room in which Jack, Algernon, Gwendolen and Cecily are tortuously justifying their intentions to become engaged despite the myriad deceptions that have occurred, that her daughter intends to marry Jack/Ernest. The two young couples have just partaken in a form of verbal give-and-take intended to sweep aside all logic and formalize their mutual attractions -- a series of exchanges that includes the classic observation from Gwendolen that, "[i]n matters of grave importance, style, not sincerity is the vital thing" -- when into the room walks Gwendolen's mother, Lady Bracknell. Responding to Gwendolen's announcement that she is engaged to be married to Jack, the matriarch offers these comments by way of objection:
"Come here. Sit down. Sit down immediately. Hesitation of any kind is a sign of mental decay in the young, of physical weakness in the old. [Turns to Jack.] Apprised, sir, of my daughter’s sudden flight by her trusty maid, whose confidence I purchased by means of a small coin, I followed her at once by a luggage train."
The answer to the question -- how does Lady Bracknell find out where Gwendolen has gone -- then, lies in the above quote from The Importance of Being Earnest. Lady Bracknell bribed the maid to ascertain her daughter's whereabouts. Deception having been central to the major characters' lives, it is only appropriate that the personification of the proper British social mores in Wilder's play should resort to the less-than-socially-appropriate method of bribery to attain the knowledge she needs in order to have any hope of manipulating her environment.