I have been given a blagdon cob, he is sort of black roan with a big white splash on his belly and four white socks. Would he be classed as a coloured for showing?
I have shown my boy, who is a blagdon cob, in quite a few cob and veteran classes, and judges have sometimes commented that he is actually also a 'coloured' as he is a black/grey/dark brown roan but with a small splash of white under his stomach, and four white socks- obviously the socks don't count but they have been referring to the splash. I didn't know about the line mentioned above.
I imagine you'll be fine in coloured classes unaffiliated/local but I don't think the belly slash would be enough to count as coloured at a higher level.
Look on bspa or chaps website, they give good descriptions on minimum about of coloured required