Cheers folks.
@Amalric: the skin colour is achieved using a triad of GW's new paints. First Rhinox hide, then a layer of Doombull brown, a wash of Agarax Earthshade, layer of Doombull brown and final highlight of Tuskgor fur.
@Vanvlak I do indeed have some berserkers. I bought them second hand on eBay to replace ones I'd sold so they need their previous attempted paint jobs stripped first.