Actually it has a few origins ...black enamel bastard , black and amber bastard or just plain black bastard . There's a sect of Masonic Orangemen over here known as the black perceptory..who wear black sashes . Also the traditional colour of the RUC uniform and the B specials uniform was black too ...a very dark green that looked black .It can basically be interchanged between cops and loyalists in equal measure . In fact in its fullest sense it actually means " bigoted bastard " , ironically enough . Idiotic to be shouting it in England obvs .