David Mcgillivray wrote in
The Monthly Film Bulletin: "Giles Cooper's TV play was in turn adapted from his 1957 radio production, and no doubt the nightmare fantasy of Lower Five B was most convincing when suggested only in sound. The trouble with the film version is that Ebony's improbable boys, devoid of individuality and bristling with
Lord of the Flies-style menace, now clash disconcertingly with their surroundings, a very real establishment in Llandudno. To go with the genuine locations, there is a genuine-looking, crumpled-collared staff and an array of ink-stained pupils who are not patently fresh from the stage school. Ebony himself is easily recognisable as a teacher struggling hopelessly to discipline a class of delinquents, and David Hemmings' performance succeeds in communicating the feeling of desperation that inexperience fosters. But while John Mackenzie's capable direction suggests a greater involvement with his material than in his earlier
One Brief Summer (1971) (although an inclination towards fussy camerawork – in the contrived linking shots – is still present), the nightmare violence is never entirely persuasive. One is more inclined at the close to echo Ebony's dismayed "Why did they do it?" than to ponder on the sinister significance of absence." The BFI's
Screenonline called it "a finely wrought psychological suspense drama". Mackenzie later said he was "proud" of the film.
Variety said "The viewer may be both intrigued and puzzled, for while film is a compelling piece of dramatics about innocent-looking terrorists, it asks a great deal of credence."
Leslie Halliwell said: "Macabre school story which overreaches itself and peters out." The
Los Angeles Times called it "a beautifully polished piece of business." ''
Leonard Maltin's Movie Guide'' rates the film three stars, calling it a "nifty little sleeper... creepy, chilling mystery, loaded with twists..." ==References==