Bantam A1847 (1959)
London was wrapped in fog when Inspector John Cheviot got into a twentieth century taxi. The city was still fogbound when he got out - but the cab was a hackney coach, the year was 1829, and murder was a safe and profitable business. There were things Cheviot remembered but couldn't use - like how to analyze fingerprints; and things he didn't know that he could have used - like how advanced his romance with the luscious Lady Flora really was. And there wasn't time to learn, because Cheviot suddenly found himself pitted against the cleverest murderer of his career.