There is an Alehouse in Yonder Town has been found in pretty well every part of England (though it's usually called Died of Love or A Brisk Young Sailor Courted Me); oddly enough, I haven't yet found any reference to a Cornish set (apart from the Traditional Ballad Index, which doesn't give details), beyond one example of a related though distinct song, A Ship Came Sailing over the Sea (Deep in Love) from Saint Enoder which, though it shares some elements, doesn't mention alehouses.

A number of tunes have been used, but the ones I've come across bear little resemblance to the Tavern tune, which was presumably composed specially.  As to derivation, Anne Gilchrist (A Guide to English Folk Song Collections, 1954) commented: "Died of Love is the stock from which many fragmentations treated as separate songs have been made, including the modern burlesque There is a Tavern in the Town. "

There is an extensive list of links to related material in this thread:  I Wish, I Wish.  Although Sheffield Park and The Butcher's Boy share some elements (as indeed does Waly Waly), their narrative element really places them in different categories.