The Railway Children by E Nesbit
After their father's sudden disappearance, Roberta, Peter and Phyllis must leave their London suburban home, with its servants and toys, for a life in the country. They are soon enraptured by the nearby railway, with its trains like dragons flying past and all the bustle of the station. Soon they find the railway also brings excitement, danger and mystery and life-changing friendships. This much-beloved children's classic brings to life to a vanished rural England.