That really does look like an Underground tunnel, doesn't it? And with that Whitechurch Underground station promo, I think it's safe to say we'll be getting something based around the London Underground. However this whole "mind bending" marketing thing then wouldn't make sense, because the only thing that bends my mind in the Underground is the amount of time between each train. So something has to be happening in the Underground. Which screams out to me, either:
Victorian, crime-related thing (which I would hate), or...
Doctor Who IP.
And with all the speculation that says the same, I'm leaning towards the latter here.