This movie tells the story of Alan Bennett's (Alex Jennings') strained friendship with Miss Mary Shepherd (Dame Maggie Smith), an eccentric homeless woman who Bennett befriended in the 1970s before allowing her temporarily to park her Bedford van in the driveway of his Camden house. She stayed there for fifteen years. As the story develops, Bennett learns that Miss Shepherd is really Margaret Fairchild, a former gifted pupil of pianist Alfred Cortot.