'Black' is used in Ireland to mean 'dark-haired' - at least it is in the Republic of Ireland. I well remember working in a place and admiring a handsome, winsome new worker with glossy black hair on the far side of the room, around 50 metres away. I turned to a colleague and said "What's the name of that little black fellow over there?" and a Northerner whipped around, astonished, and stared wildly (black people in the more usual sense being a rare novelty in Irish workplaces of the time). "Where? Where?" "Over by the window, there!" He was still staring back and forth, baffled, when there was a chorus from the colleagues around me naming the little black fellow.

In the song, "Some say he's black" suggests also that he was swarthy, which was out of fashion and considered ugly until the suntan craze that started in the 1920s and made those lucky people who tanned easily now be the beauties.