Rose asks if she's allowed to be where she is. Her automatic response to officialdom of any kind is to question her own status. For all her confidence, she's a girl who lives on an estate and worked in a shop.
The young woman in overalls looks awkward.
"You have to give us permission to talk," she says, nervously aware of the irony.
Rose is dumbfounded. She realises that this woman looks upon her - Rose - as a high status person, someone before whom she must be humble.
"Er..." she says, embarassed, "you... have... permission?" She inflects it as a question. 'Is that the right form of words that I'm using?' There is embarassment in her voice, and a faint look of nausea on her face. It makes me love her.
"Thank you," says the woman, who's name turns out to be Raffalo, "And, no, you're not in the way. Guests are allowed anywhere."
Rafallo turns out to be a plumber. She addresses Rose respectfully as "Miss". Rose probably feels like a teacher.
"They still have plumbers?" says Rose, stating it to herself as much as asking a question. Five billion years in the future and there are still grease monkeys in boiler suits, running around backstage, making sure the swells have plenty of hot water.
"I hope so," says Rafallo, "else I'm out of a job."
Just like Rose is out of a job now that, between the Autons and the Doctor, the shop where she worked got blown up. Rose knows what unemployment means.
Rose says goodbye and, as she leaves, Rafallo thanks her "for the permission".
Rose has met one of the people in the background. The people who make everything work. One of the people the Doctor has never had much to do with until now. But Rose would, because she was one of those people herself, until recently. Now she's travelling. Rafallo will not be as lucky, despite being Rose's mirror image. Because the universe is shitty and unfair. Still. Rafallo is about to die because of the profiteering scheme of a rich, sociopathic bit of skin who also happens to be the last human being alive... if we allow that she's still human at all (and that Rafallo somehow isn't).
It's a shame that Cassandra is the show's first explicitly transgender character. And it's also a shame that we, the people of the universe, are depicted as still ridden by class in the year 5 Billion. As Slavoj Žižek said:
Think about the strangeness of today's situation. Thirty, forty years ago, we were still debating about what the future will be: communist, fascist, capitalist, whatever. Today, nobody even debates these issues. We all silently accept global capitalism is here to stay. On the other hand, we are obsessed with cosmic catastrophes: the whole life on earth disintegrating, because of some virus, because of an asteroid hitting the earth, and so on. So the paradox is, that it's much easier to imagine the end of all life on earth than a much more modest radical change in capitalism.
He said that in 2005.