I can't remember when "coloured" was ever used in a pejorative context tho. An MP used it on the record the other month (can't remember who) and got in trouble. Clearly they didn't think it was an offensive/abusive term.
When you think about it, "coloured" and "black" are both equally wrong from an accuracy perspective, so why one "causes deep offense" and the other is normalised, well it's purely an invention really. A social faux pas maybe but an invention that exists purely to trip people up (normally the well-meaning - those who *want* to cause offense would use other words!)