"The success of "An Inspector Calls"

For example, at the end of Act III Mrs. Birling has just learnt that Eric fathered Eva Smith's child and just as he walks in and you expect Mrs. Birling to become furious with him the curtain falls making you wait a few minutes to find out what happens. Priestley benefits from this in that he keeps people interested and always wanting to know what path the story of the play will take. Between acts there may be an interval or a curtain-down for a period of time, this entices the audience to really think about the play and what will happen, maybe even discuss it with those around them in the theatre. All in all these devices are all used to bring the play more to life and involve the audience in a way so that they feel concerned for characters and feel emotion in the same way that the characters are meant to.
             At the start of the play the mood is very relaxed, the family are celebrating the engagement of Sheila and Gerald, the audience feel at ease with what is taking place on stage and the world of the Birling's at this stage seems trouble free, of course - this soon changes. Mr. Birling wants to make a good impression on the new member of the family, Gerald; in the opening lines of the play Mr. Birling points out that the port they are having is the same as the port that Gerald's father buys from the merchant. We are told that the merchant informed Mr. Birling of this similarity but it is obvious he asked which port Gerald's father bought and has used this to impress Gerald, this may be a way in which Mr. Birling is trying to "climb the social ladder" to one on a par with the Croft family and his wife. By writing Priestley is making a social comment that Birling is prepared to go out of his way and go to quite long lengths to get into the higher classes, an example of how important class is to Mr. Birling and other men in a similar position to his at this time.
             Another sign that the feel of the play is becoming a little tenser is the way in which Sheila reacts to comments from Gerald about how long he has been trying to get into the family.