E. Nesbit 
The railway children [EPUB ebook] 

The Children Railway is a children’s book. Bobbie, Peter and Phyllis live in London with their parents. Their happy life is interrupted by the father's arrest and the country's move to his mother in a house near the railroad. The money is scarce and the children are worried. They spend a lot of time on the railroad, greet passengers of London-based trains. When a senior gentleman receives the greeting, Bobbie decides to ask for help from her father. A fun story, full of hope and love.