New Doctor Who companion

Pretty anticlimatic, alas. And if you're in the fandom, or the UK, you're undoubtedly going to be spoiled for it very shortly, but the name of the actor playing the new companion's under the cut.

( New Doctor Who companion )

I want them to bring some other news. More exciting news. Like the Madame Vastra and Jenny spin-off of my telly dreams.

ETA More details about when people leave/turn-up, details on Ponds' exit: ( spoilery )