I have recently researched the characters in the song "Colonel Wyndham" and "Jim Norris" and come up with this http://books.google.co.nz/books?id=2XoEAAAAQAAJ&pg=PA104&lpg=PA104&dq=colonel++g.wyndham+%22James+Norris%22&source=bl&ots=uyvzA_ from "The New Sporting Magazine" of January 1837.

Colonel G. Wyndham was, in fact George Wyndham, 1st Baron Leconfield (1787-1869) who was the son of George Wyndham, 3rd Earl of Egremont (1751-1837) and lived at Petworth House, in West Sussex.

Noting the age of the tune, and that the "Black Sloven" was a horse from an earlier time and a different part of England, I can only imagine that the song was popular throughout the hunting districts of England and worked on the idea of "insert name of Master/Huntsman/Whipper-in here" at appropriate places in the song.
Best Wishes, Kevin Mayes.