Indeed the song comes from Thomas Arne's little opera 'Thomas and Sally' of the early 18thc (not 17th). The original words were by Isaac Bickerstaff. The song was so popular that it was sung independent of the opera at the pleasure gardens throughout the 18thc. The original survived almost intact to be collected c1900, but the well-known version sung in folk clubs and much collected must have been rewritten by a broadside hack about 1800 which is when it began to be widely printed on broadsides. The song like most of its type was written in London and the inclusion of a nightingale is simply poetic licence.