Carrie's War / Nina Bawden

Set in WW2, Carrie and her little brother are evacuated to Wales and billeted at the home of the bullying Mr Evans and his timid sister Lou. Unhappy at home, they love visiting fellow evacue, Albert, at the farm of Druid's Bottom. Here they meet Hepzibah Green, who knows magical stories, and Mister Johnny, who speaks a language all his own. But then things go wrong and Carrie takes things into her own hands - without guessing the awful consequences.