I always wondered . . .
. . . How this film would have been if Nigel Kneale had scripted it, with Val Guest directing.
In many ways it bears similarities to their Quatermass Films and ABOMINABLE SNOWMAN (which Tucker co-starred in). But I'm sure CE was not a Hammer Production like the previously mentioned.
Many of the same elements; mysterious disappearences and grisly deaths, off-screen monsters (until the finale), sense of mounting tension and suspense, etc.
And the girl's telepathic contact with the creatures brought ABOMINABLE SNOWMAN to mind.
As fond as I am of it, it did tend to slip under the Quatermass Films, perhaps due to a more limited budget and rushed production.
Still a favorite that's most effective at 2:00 AM.