Edith Nesbit 
The Railway Children 

This story is about a family who moves to a house near the railway after the father is imprisoned as a result of being falsely accused of selling state secrets. 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 always takes the 9:15 down train.