Re Malcolm Douglas's post earlier about Joseph Taylor's singing style. I remember reading somewhere that he learnt some of his songs from gypsies as a youth, particularly Brigg Fair, the tune of which is part of The Star of the County Down. It may well be that he picked up elements of the travellers' singing style too.
He had a very open delivery, reminiscent of church choirs. So his singing style may have been an amalgam of many influences and may have evolved over time.
I think that is what happens with most singers - they don't suddenly appear on a stage fully formed. They evolve and change over time, absorbing influences from here , there & everywhere, rejecting many and retaining the ones they feel appropriate.