Here is an interesting find. I ran across this one while searching for an article on Lord Peter Wimsey. I have reproduced the text for you that accompanied the stamp.
The hero of Dorothy L. Sayers first police novel, "Whose Body?" (1923), was a detective called Lord Peter. Later the well-known personage of Lord Peter Wimsey reappeared in "Strong Poison" (1930) and in "The Nine Tailors" (1934). Thin, good-looking, sporting a monocle, Wimsey was the perfect aristocratic detective -- elegant and excellent. There was something in his aristocratic nature which led him to try and hide his talents as an investigator, and he was one of the only detectives who found time to marry.
There are plenty available at this web address. http://www.trussel.com/detfic/detect.htm