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.
Virginia McKenna
as Mrs. Walker
Ronald Fraser
as Uncle Jim
Suzanna Hamilton
as Susan Walker
Simon West
as John Walker
Sophie Neville
as Titty Walker
Stephen Grendon
as Roger Walker
Kit Seymour
as Nancy Blackett
Lesley Bennett
as Peggy Blackett
Brenda Bruce
as Mrs Dixon
Mike Pratt
as Mr Dixon
John Franklyn-Robbins
as Young Billy
Jack Woolgar
as Old Billy
