The origins of the Harry Lime story are shadowy. In his autobiography, Ways of Escape, Greene relates how in 1947 he had scribbled an idea for the opening of a story on the back of an envelope: ‘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.’ That was it – one sentence. Greene went to Vienna early the following year in order to develop the story. After two weeks, Greene claimed, the story was still no further advanced until he met a British Intelligence officer who told him of the city’s vast sewer system and the black market in penicillin. Greene had found his plot.

However, a slightly different story is told by the surviving documents. In his book, In Search of The Third Man, Charles Drazin shows conclusively that Greene already had the beginning, middle and end of The Third Man a good five months before he visited Vienna. As early as September 1947 he wrote to his lover Catherine Walston:

Tonight … I felt restless, so I walked all up Piccadilly and back and went into a Gent’s in Brick Street, and suddenly in the Gent’s, I saw the three chunks, the beginning, the middle and the end, and in some ways all the ideas I had – the first sentence of the thriller about the dead Harry who wasn’t dead, the Risen-from-the-dead story, and then the other day in the train all seemed to come together. I hope to God it lasts – they don’t always.

Twelve weeks later, in December 1947, Greene and his director friend Carol Reed were invited to dinner by the film producer Alexander Korda at his offices in Piccadilly. Talk was of Reed’s recently completed movie The Fallen Idol, based on Greene’s mesmeric tale about the corruption of childhood innocence, ‘The Basement Room’. Greene had begun this story – one of his best – on his way home from Liberia in 1935 on board a cargo ship. It tells of a small boy who has been left alone by his parents in a grand London house in the care of their butler Baines and his jealous wife. The seven-year-old Philip wants to see what lies beyond ‘the green baize door’ – the dark basement inhabited by Mr and Mrs Baines – and he embarks on a hazardous exploration of the grown-up world. Philip is clearly devoted to the butler and idealises him quite as much as Rollo Martins had idealised Harry Lime. Eventually the hateful Mrs Baines is killed by her unfaithful husband, and the boy is innocently forced to betray the butler to the police. He remains emotionally scarred by his betrayal.