Why did the man say that people in his picture might be from the 19th century?

Listen to the conversation, and mark each question as A, B, C or D according to your listening.
David: OK, so we’ve got to describe our pictures to each other, who starts...
Maria: Go ahead, you start.
David: OK, well, we can see a group of people sitting on a bus. It’s not in the present day. It’s maybe sometime in the 19th century, because they’re all wearing old-fashioned clothes, you know, hats and big dresses...
Maria: And where do you think the place is?
David: It’s probably London—the adverts on the bus are in English, in any case, and it’s in a town. I mean, these look like city people, not country people.
Maria: So can you see any buildings in the background?
David: Well, no, there are trees—I think it’s a park, actually, and there’s a horse which is pulling a smart black carriage, hmm... and I think it’s raining, not sure, but anyway, two of the people who are sitting on the bus are carrying umbrellas.
Maria: So how many people are there?
David: Five adults, one child, and a baby. There’s just one man, and he’s reading a newspaper— he looks like a rich banker or something and he’s wearing a smart suit and a top hat. The woman who’s sitting on the far left is a young mother with the baby in her arms and the child—a little girl—sitting next to her, and they seem to be quite poor, and then the woman who’s sitting next to them, she looks quite rich—the dress she’s wearing looks expensive, and then next to her is the rich banker, and next to him another young woman who’s dressed all in white—perhaps it’s a nurse’s uniform or something, and then finally there’s a young woman who’s getting on the bus and she’s holding a white box—I think it’s a hat box.
Maria: Are any of these people talking to each other?
David: No, no, they’re all just sitting there staring out of the window or reading the paper or whatever. Oh, that’s strange—there’s something right on the far left of the picture and it’s sort of like an old woman who’s sitting next to the young mother, but it’s impossible because that’s where the front wall of the bus is. I don’t know ... she looks like a ghost or something. I didn’t even notice her at first...
Maria: So you think it’s a ghost?
David: I don’t know. Maybe the artist was going to paint a woman then changed his mind.
Maria: Hmm, sounds strange. Right, well, my picture’s similar. It also shows some people on a bus...