''The Lady in the Van'' tells the true story of Alan Bennett's strained friendship with Miss Mary Shepherd, a crabby, eccentric and insanitary homeless woman whom Bennett befriended in the 1970s before allowing her to park her Bedford Vehicles van in the driveway of his London Borough of Camden home "for three months". She stayed there for 15 years. As the story develops Bennett learns that Miss Shepherd is really Margaret Fairchild, a gifted former pupil of the pianist Alfred Cortot. She had played Chopin in a The Proms, tried to become a nun, was committed to an institution by her brother, escaped, had an accident when her van was hit by a motorcyclist for whose death she believed herself to blame, and thereafter lived in fear of arrest.