The film offers a particularly believable picture of a highly intelligent child. Here Martha Byrne giving a standout performance of fierce determination – particularly good is the psychological battle between she and Dina Merrill. The way in which the story eventually allows her to grow up and soften is quite touching. The result is a surprisingly intelligent fable about growing up, which has been allegorically cast as a self-determination vs genetic predeterminism parable.

Another surprise is the twist revelation at the end – which contains a good performance from Jack Gilford who slides between a grandfatherly warmth and cold manipulation with disturbing regard. It’s an ending that holds considerable fascination as much for the surprises it unveils as for the ambiguity it leaves a genre such as the children’s film which traditionally relies on happy resolutions to end on.

Where the film falls down considerably is in its utterly flat and dreary directorial style. It is largely a cerebral and story-driven film and the attempts to pump up excitement with grafted-on biplane chase sequences seem badly out of place.