Answering the Call

Amy believes 'Granny Wren' is so called because she is small and frail, like the bird. But Granny was a Wren in World War I - risking all delivering messages on her trusty Douglas motorcycle. So very brave and not frail at all. To Amy, her Granny is now a hero. So why then is Amy's mother determined that her daughter must stay well away from 'Granny Wren' ?