‘It wasn’t like that in the book’ is one of the commonest and most irritating responses to film versions of famous novels. Adaptation of literature to film seems to be a topic of enduring interest at every level, from foyer gossip to the most learned exegesis. Sometimes, it must be said, the former is the more entertaining, but this is no place for such frivolity.

There are two contrasting and equally unproductive approaches to this phenomenon. The first one, favoured by those whose background is wholly in film, holds that ‘a film is a film’ and that there is no place for consideration of its literary antecedent. The second is to invoke the notion of ‘fidelity’ to the source book as a yardstick for evaluating the film adaptation. I want to suggest that it is all but impossible when viewing the film version of a novel one knows well, and values, not to have the novel in mind at some level of consciousness; and that fidelity, though admirable in marriage, is beside the critical point.