Swallows and Amazons (1974)

Director: Claude Whatham
Cast: Kit Seymour, Lesley Bennett, Ronald Fraser, Simon West, Sophie Neville, Stephen Grendon, Suzanna Hamilton, Virginia McKenna

Synopsis:

On holiday with their mother in the Lake District in 1929 four children are allowed to sail over to the nearby island in their boat Swallow and set up camp for a few days. They soon realise this has been the territory of two other girls who sail the Amazon, and the scene is set for serious rivalry.