Davies is a low-ranked CID (mentioned as a detective constable at least once) officer in the London borough of Willesden. He is nicknamed "Dangerous" ironically because he is said to be harmless. His real first name is never revealed. In the novels and TV series he is called "The Last Detective" from his superior's assessment of him as "the last detective, since he was never dispatched on any assignment unless it was very risky or there was no one else to send". Despite this, Davies is by no means a poor detective, and although he can take longer than his colleagues, and is dogged by bad luck, he does usually "get his man" in the end.