Where does the phrase not my bailey wick come from?

There is no phrase "not my bailey wick." The correct phrase is "not my bailiwick." The word "bailiwick" is derived from the Old English word "baili," which means "steward" or "agent." It originally referred to the district over which a bailiff had jurisdiction. Over time, the meaning of the word expanded to include any area of responsibility or expertise. Today, the phrase "not my bailiwick" is used to indicate that something is outside of one's area of knowledge or responsibility.