Mr. Hudson. In the original Sherlock Holmes mysteries, he and Watson relied upon Mrs. Hudson, who lived downstairs at 221 Baker Street and served as … well, housekeeper and cook. I felt there needed to be a Hudson on the premises in my own series, but opted for a slightly different head of the household. And so Thomas was added to my cast.

Close crop from “Hudson & Holmes,” one of the portraits that Mart Lett, series illustrator, created for the art card series that I have been sending ou...