I believe that he original tune to 'Byker Hill' was, according to Allen's Tyneside songs, 'Off She Goes'. But the premise that the originator of this thread states, is pretty much correct. Try playing, 'Jingle Bells' using any notes or indeed no notes (just bang it out on a table) it will still be recognisable as 'Jingle Bells' because tunes are defined mostly by their rhythm rather than their tonality. This means that in changing the rhythm you are essentially changing the tune.