The Monthly Film Bulletin wrote: "[The] suggestion, that the extraordinary, the nightmarish is simply one step further on from the everyday, is effectively evoked throughout the film by James Wilson's restless, prowling camera, by judiciously timed shock cuts, by the use of over-lapping dialogue, with sentences half-finished and characters cutting each other short."
Kine Weekly wrote: "The eeriness of the opening scene when the invaders land and cause widespread electrical failures is well done, but the mystery is sustained too long while nothing much of consequence happens. ...The space craft, by the way, fly impressively."
Leslie Halliwell said: "Understated, effective liitle suspenser, well done in all departments."
The Radio Times Guide to Films gave the film 2/5 stars, writing: "Aliens put an invisible force field around a secluded country hospital in this endearingly daffy British oddity, which must feature the cheapest alien takeover in history. Edward Judd is the scientist battling the extraterrestrial Oriental women in spacesuits, in an efficiently made and, yes, mildly exciting slice of cut-price science fiction. Director Alan Bridges imbues the Home Counties atmosphere with a peculiar ambience that's astonishingly heady at times." Andrew Roberts at
BFI Screenonline wrote: "Alan Bridges' background in television plays and B-films allowed him to create a wholly believable cottage hospital based on what was virtually a single set, while the screenplay ... manages to evoke some usually plausible alien 'invaders'."
The Encyclopedia of Science Fiction praised Alan Bridges' direction, saying that he "creates a powerfully strange atmosphere despite a very small budget." ==References==