The 'gallowa' pony was the standard pit pony in Co Durham and was of small stature for obvious reasons and that's what Jez's song is about- doubt if the 'Scottish Galloway' as described by the Fell Pony Museum would have been suitable for the work. As one who lives (lived) in Galloway I often wonder at the name, but the only explanation I've had locally is that they were fell ponies of some sort, but bred specially in Galloway for use in the pits of Durham- don't think there is such a breed these days, except maybe a few ageing retirees, although even that's now unlikely, 20 years after the last Durham deep mine closed.