In the 1970s, an eccentric old lady called Miss Shepherd lived in an old van opposite Alan Bennett's house. That is until new parking regulations come into force. He suggested moving the van onto his driveway. The resulting odd relationship - not quite a friendship - lasted for 20 years until Miss Shepherd's death. The play is based on entries from Bennett's diaries of the period. Bennett uses the situation to explore the line between acceptable and unacceptable mental illness; the troubling contrast between his care of Miss Shepherd vs. comparative neglect of his own mother; and the various ways in which even the officially sane can deny reality.