Quote Originally Posted by dps View Post
First, do you have a source for that assertion? True, there haven't been any instance of purely mundane threats since 1982, and before that none since very early in the 2nd Doctor's run, but I'm not aware that it's a set policy by the BBC.

Second, technically neither Silurians nor gangers are extraterrestrial. And maybe not the Silence, either, but that's not quite clear. And that's just limiting it to threats faced by the 11th Doctor. But if your assertion is true, I guess all 3 and other, earlier examples, might be close enough.
You make a good point about the Silurians being terrestrial. I was sorry that the dinosaurs in space episode didn't have any actual Silurians in it.

I too would like to see the source of the claim that the BBC requires an extraterrestrial threat in every episode. I mean I can believe it, but I'd still like to see some evidence.