The Railway Children

A family move to a house near the railway after the father is imprisoned. The three children, Roberta, Peter and Phyllis, find amusement in watching the trains on the nearby railway line and waving to the passengers. They become friendly with Perks, the station porter, and with the Old Gentleman who regularly takes the 9:15 down train. He is eventually able to help prove their father's innocence, and the family is reunited. (Wikipedia)