Where does the phrase That's not my bailey wick come from?

A bailiwick /ˈeɪlɨwɪk/ is usually the area of jurisdiction of a bailiff, and once also applied to territories in which a privately appointed bailiff exercised the sheriff's functions under a royal or imperial writ. The Word is now more generally used in a metaphorical sense, to indicate a sphere of authority, experience, activity, study, or interest. A bailiwick (German:"Ballei") was also the territorial division of the Teutonic Order. Here, various "Komtur(en)" formed a Ballei province.

The term survives in administrative usage in the British Crown dependencies of the Channel Islands, which are grouped for administrative purposes into two bailiwicks-Jersey (comprising the island of Jersey and uninhabited islets such as the Minquiers and Écréhous) and Guernsey (comprising the islands of Guernsey, Sark, Alderney, Brecqhou, Herm,Jethou and Lihou). A Bailiff heads each Channel Island bailiwick.