What did the villagers whistle when they saw the stranger?

From the text:

There was a song popular at that time called "The Bogey Man". Miss Statchell sang it at the schoolroom concert (in aid of the church lamps), and thereafter whenever one or two of the villagers were gathered together and the stranger appeared, a bar or so of this tune, more or less sharp or flat, was whistled in the midst of them. Also belated little children would call "Bogey Man!" after him, and make off tremulously elated.