Time Out says
The third and most interesting of
's Quatermass parables, scripted without interference by Kneale himself from his original TV series, so that his richly allusive web of occult, anthropological, religious and extraterrestrial speculation emerges intact as excavations at a London underground station turn up what appears to be an unexploded Nazi bomb, but proves to be a mysterious space craft. Hammer unfortunately delayed filming for several years, partly because of the sheer elaborateness of the subject matter, and partly because the plot did not lend itself to instant monster treatment. By the time the project came to be filmed, the company had moved from Bray and much of the atmosphere of their productions had been lost; but the brilliant pre-Von Daniken anthropological theme of Kneale's script still guarantees interest.
Cast and crew