Known as a short book, The Lady in the Van does not seem an obvious candidate for dramatisation. Yet Alan Bennett proves again that his theatrical instinct is sure, even though his director, Nicholas Hytner, might have had more to do with its assured success than meets the eye. Then he has the inestimable benefit of Maggie Smith in the role of the cantankerous old woman whose ramshackle van, in which she lived, landed in Bennett’s front garden, where it remained for 15 years. Smith, while always worth watching, has been inclined towards mannerism over the past few years , but here she is almost unrecognisable in her tattered garments, her pinched face glowering beneath a ludicrous baseball cap. It is a masterly performance, as she drops hints of artistic upbringing and personal mysteries which she is reluctant to explain. She is a nightmare of the elderly relative who dominates the circumstances in which she finds herself. She accepts generosity as a right and laments the decline of every kind of standard while she falls short both in manners and personal hygiene.

Masterly too is the way in which the author splits himself in two so that there are two Bennetts on stage, played by Nicholas Farrell and Kevin McNally. One is Bennett the resident relating to his neighbours, torn between compassion and hatred for his unwanted tenant. The other Bennett is the more detached writer, the compulsive chronicler of events that he will incorporate, almost guiltily, into his own books. It is a piece that combines Bennett’s unfailing sense of humour with observations of considerable depth, enhanced by Mark Thompson’s composite set, which allows room for Miss Shepherd’s van, and her second home, an ancient three-wheeler, to be on stage at the same time.