...and rewatched it for the first time in over thirty years this summer as part of a general binge of kids telly.

This was then, and still is now, really good. There's a real sense of mystery and eeriness, and the young cast act really well. The music/score is excellent, and while perhaps some of the effects have dated, the story hasn't, because it doesn't rely upon them.

British kids telly used to be brilliant, didn't it?!