The opening scene of An Inspector Calls creates the sense for the audience that they will be seeing a traditional British living room comedy. Sheila is described as speaking "gaily," or happily; later she remarks that "this is the happiest day of my life." The atmosphere is playful, celebratory, and warm. Priestley embeds a hint of darkness through the use of dramatic irony in Arthur Birling's predictions for the future. A successful businessman with a strong capitalist sensibility, Birling claims that technological advances will surely erase the need for war. Priestley's audiences would have understood that technological advances did, in fact, play a major role in creating the horrors of World War I.

In another example of irony, Birling describes the ill-fated Titanic: "Why, a friend of mine went over this new liner last week—the Titanic—she sails next week—forty-six thousand eight hundred tons—New York in five days—and every luxury—and unsinkable, absolutely unsinkable." Of course, we know that the Titanic did, indeed, sink.

When the Inspector arrives, Priestly describes a shift in the lighting, with a "harsh bright light" replacing the traditional soft theatre lights. This indicates to audiences that the warm, convivial, and traditionally Victorian atmosphere was, in a way, artificial and is about to be exposed for its dark truth.