MacColl was not discussing the 'style' but the "idiom" - that the songs, in both cases, had been taken from one idiom and had settled into another
Of course there are varying styles, but the one displayed by Charlie Scamp and deliberately adopted by newly had changed the utterance of the song which acted against its storytelling function.
All British folk styles, wherever they were found, were used to accentuate the narrative - the singers were storytellers.
I presume by "Jimmy" you mean MacColl (oh dear - not you too!!).
Ewan was not a traditional singer and always took great pains to point this out; his approach to the songs he sang was a deliberate, self-conscious one - that of a revival singer who explored and used various styles of singing.
When Betsy sang she, like most of our field singers, was remembering a way of singing that was long gone - her tradition was dead and had long ceased to develop - apples and oranges.
As far as I can see, Charlie Scamp's approach was that of the Traveller brother I described, a rejection of any form of traditional approach, changing what was being communicated by the song.
His sister, on the other hand, sang much nearer to a traditional style and, in my opinion, maintained the feel for the content of the song far more successfully
Tom Lenihan, from Clare and Walter Pardon both dealt with this over and over and at great length   
Jim Carroll