Originally cut to one hour and 29 minutes and was the second feature on a double-bill with Torpedo Run (1958). For a DVD release in 2013, it was restored to a running time of one hour and 40 minutes.
Importantly, the film marks the appearance of Dame Maggie Smith in her first major film role as "Bridget Howard" (she had previously appeared in a bit part in Child in the House (1956). She makes an indelible impression as a somewhat disillusioned but impulsive woman who places her trust in men that don't deserve her.
Donald MacKenzie, the author of the original novel, specialized in works of fiction centering on criminal activity, rather than detective work. He had been a criminal in real-life and had served time in prison. Writer and Director Seth Holt described him as "one of the prison intelligentsia."
When Maggie Smith finds out that her fiance has, without telling her, gone to Tangier, she says that that confirms what she suspected. She says, "He had a problem, and I was helping him with it." An audience of the time would understand this to mean homosexuality, as Tangier was notorious as a place for young male prostitutes. Anyone not getting it would get some more help from a newspaper story which is then shown, saying that the fiance lost his job as a result of a court appearance, the crime for which is not mentioned.