Doctor Who episode 388: The Ark in Space – Part Three (8/2/1975)
The Quatermass inspirations remain pretty clear in this episode. Apart from Noah’s Carroon-like transformation, and the squirming Wirrn in the solar stacks that recall the aliens in the vats in Quatermass II, we get the Doctor’s version of Quatermass and the Pit’s optic-encephalogram, a device that allows him to relive the history of the Wirrn Queen’s infiltration of the Ark. It’s a good sequence, but the really disturbing thing about it is the Doctor’s reaction: mentally linked to the Wirrn, he seems subsumed by its intelligence, to a point where he walks towards a menacing grub, as if seeking to join with it, and has to be physically restrained by Sarah Jane. All this cosmic horror is entirely Nigel Kneale (or at least Hammer’s full-bodied adaptations), much more so, in fact, than most of Season Seven.