How are the Birlings presented as Affluent?

The scene is set one evening in the spring of 1912 in the dining room of the Birlings’ house in Brumley, an “industrial city in the North Midlands” of England. Priestley specifies that the room has “good solid furniture” and is “heavily comfortable, but not cozy and homelike.” The home is full of fine surroundings and art. It is clearly a luxurious place.