In An Inspector Calls Priestley quickly establishes Arthur Birlings character by his setting, in a comfortable middle class house during a dinner party, by what he says and how he says it.
Remember that nothing in a play or in a film happens by accident. Everything on stage or on the screen is designed to be there to achieve a particular purpose.
He starts by calling out Shiela who is admiring her wedding ring, his little (sic) speech comes directly after the formalisation of her engagement and in a way he is trying to get the lime light back onto himself. His words are telling “I don’t often make speeches at you -“
He goes on to make a speech where everything is wrong and the audience would have known it to be very, very wrong. Set before 1912 this speech is a riposte to what Birling sees as pessimistic talk. Talk of labour disputes, war and the Titanic.
As we all know the Titanic is the most famous ocean liner in history, for all the wrong reasons. Birling is interested in the material facts of the Titanic, its size and speed, whereas it has become famous for the tragic loss of life and mythos. This would not be lost on the audience who would be confirmed in their suspicions that despite claiming to be a hard headed man of business who can take a sensible reading of the situation. In fact he is completely wrong and set up in the eye of the audience as a buffoon. A buffoon who by the end of the play knows his family as well as he knows current events.
In the same way as the Titanic the Birling family are big, rich, influential and powerful in their little town but by the end of the play this Titanic hits the iceberg of reality and is itself wrecked.