Quatermass
Nigel Kneale's professor brought back a fourth time, thirty years after the BBC serials that invented British television science fiction.
1 sequence
Season 1
No usable clip kept. The copy offered as opening credits belongs to The Quatermass Conclusion, the feature-length edit, and says so on its own title card. The serial's own upload runs the opening and closing credits together rather than the opening alone.
No footage of this sequence has been found yet.