Tiger in the Smoke (1956)

Having been sent a picture of her husband, a war hero killed in France, Meg Elgin is led to believe he is still alive and arranges a meeting at a London railway station. When she arrives there with the police accompanying her, she catches sight of a man in the distance wearing an old coat of her husband's. When he is pursued and captured, he turns out to be Duds Morrison a former soldier and out-of-work actor recently let out of prison. He refuses to tell them anything, and having nothing they can charge him with, the police release him. His interest aroused by the pictures sent to Meg, her new fiancé Geoffrey Leavitt follows Morrison and tries to demand an answer from him about his sudden appearance masquerading as Meg’s dead husband.