Tell you what- you play it your way & stop criticicing the way others do it.
I've no doubt Jimmy Shand had influence all over England but whether the Bulwers' version was inspired by JS' version of a much older tune cannot now be discovered & why does it matter- they may have ADAPTED it to the English tradition, and why not?
Your implication is all should play the'correct' versions- decreed by you I suppose?
That's crap- things change- such tunes are often played differently by the same person from one day to the next- or if not it b.... well should be- that's the essence of 'folk' music and half the fun!!- there's no straitjacket, unless you listen to Jack Campin, of course