Rose: And where do you think you're going?
The Doctor: Nowhere. It's, uh, just a bit human in there for me. History just happened; they're talking about where you can buy dodgy top-up cards for half price. I'm off on a wander, that's all.
Rose: Right. There's a spaceship on the Thames and you're just wandering.
The Doctor: Nothing to do with me. It's not an invasion. That was a genuine crash landing. Angle of descent, colour of the smoke, everything. It was perfect.
The Doctor: So maybe this is it. First contact. The day Mankind officially comes into contact with an alien race. I'm not interfering 'cause you got to handle this on your own. That's when the human race finally grows up. Just this morning you were all tiny and small and made of clay. Now you can expand.