Winston "Scotty" Fitzgerald (1914-87) recorded this tune in the 1950s, and followed it in medley with a tune he called The Polo March. This tandem was quickly adopted by Island fiddlers, and as of 2006 it was still quite frequently played: particularly in the eastern half of the Island. PEI fiddlers sometimes play Southern Melody on its own, but I have never encountered Polo March played separately.
Fitzgerald is said to have learned the tune he called Southern Melody while working with Hank Snow (1914-99), the Nova Scotia native who later became a major Nashville star. Some American fiddlers familiar with the Southern idiom have noted that it matches no known tune exactly, but instead may be a composite of several: most notably "I Ain't Got Nobody," a song written in 1915 by songwriter Spencer Williams (1889-1965) and later adopted by the country music industry.
Notation for this tune as played by Reuben Smith is in Fiddle Music of Prince Edward Island.