Another example 'Londonderry Aire' (aka Danny Boy). It was a long time practice in the country western field to use FOUR harps for this tune. One for the head, one for the bridge, modulate up a semi one and a third for the head and the fourth for the finale. I have always used just TWO harps for this tune even with a key change, BUT someone doing it the 'old' way would need 4 harps.
Er...works for me on just one Paddy Richtered G harp...What key-change? Sounds like it could be a truck driver's key change to me. ;-)