Most novelists, I suppose, carry round in their heads or in their notebooks the first ideas for stories that have never come to be written. Sometimes one turns them over after many years and thinks regretfully that they would have been good once, in a time now dead. So years back, on the flap of an envelope, I had written an opening paragraph: ‘I had paid my last farewell to Harry a week ago, when his coffin was lowered into the frozen February ground, so that it was with incredulity that I saw him pass by, without a sign of recognition, among the host of strangers in the Strand.’ I, no more than my hero, had pursued Harry, so when Sir Alexander Korda asked me to write a film for Carol Reed – to follow our Fallen Idol – I had nothing more to offer than this paragraph. Though Korda wanted a film about the four-power occupation of Vienna, he was prepared to let me pursue the tracks of Harry Lime.

To me it is almost impossible to write a film play without first writing a story. Even a film depends on more than plot, on a certain measure of characterization, on mood and atmosphere; and these seem to me almost impossible to capture for the first time in the dull shorthand of a script. One can reproduce an effect caught in another medium, but one cannot make the first act of creation in script form. One must have the sense of more material than one needs to draw on. The Third Man, therefore, though never intended for publication, had to start as a story before those apparently interminable transformations from one treatment to another.

On these treatments Carol Reed and I worked closely together, covering so many feet of carpet a day, acting scenes at each other. No third ever joined our conferences; so much value lies in the clear cut-and-thrust of argument between two people. To the novelist, of course, his novel is the best he can do with a particular subject; he cannot help resenting many of the changes necessary for turning it into a film or a play; but The Third Man was never intended to be more than the raw material for a picture. The reader will notice many differences between the story and the film, and he should not imagine these changes were forced on an unwilling author: as likely as not they were suggested by the author. The film in fact, is better than the story because it is in this case the finished state of the story.