Doctor: First, I've got to find it. How can you hide something that big in a city this small?

Rose Tyler: Hold on. Hide what?

Doctor: A transmitter. The Consciousness is controlling every single piece of plastic, so it needs a transmitter to boost the signal.

Rose Tyler: What does it look like?

Doctor: Like a transmitter! Round and massive... somewhere slap banging in the middle of London. (Stops walking and has the view on the London Eye behind him) A huge, metal, circular structure, like a dish, like a wheel, radial, close to where we're standing, it must be completely invisible. (Rose is looking at the London Eye) What? What? What is it? What? Oh. (he finally gets it) Fantastic!