Holmes and the Scotchman

Inspector mac donald of scotland yard was ushered into the room. The inspector looked from one to the other of us in dazed astonishment, just this said, he that mister douglas of berstone manor house was horribly murdered last night. He stammered, berlstone. Where in the name of all that is wonderful did you get those names? It is a cipher that doctor watson and i have had occasion to solve. But why? What's amiss with the names?