Who is Jimmy Dart from The Favored Child and what is their importance?

Jimmy is one of the surviving children taken from Acre and forced to work in a mill until it closed. Jimmy approaches Julia on the street in Bath, offering to light her way home. She impulsively says that she'll take him home and then discovers he's from Acre. Jimmy, along with Rosie Dench, Nat Brewer and a girl named Julie are taken under Julia's care and sent home. Julie does not return to Acre, though the other three do.