Dramatic irony. Shows the dangers of Birling's capitalistic ways.

Birling is taking an individualist, capitalist point of view about personal responsibility.

Mr Birling is trying to gain power over the inspector.

"massively" silences Birling with a put down.

Final delivery of Priestly's social message. Also links to WW2.

Birling hasn't learned his lesson.

Sheila crucially understands the importance of the Inspector.

Mrs. Birling is trying to use her wealth, power and influence to intimidate the Inspector.

Eric has also realized the importance of the situation, and has learned from the Inspector's wise words.

Gerald hasn't changed his attitude and doesn't take responsibility for his actions. He forgets how poorly he treated Sheila and Daisy/Eva.