Duke,if only life was that simple, the further you get away from known parentage, the more scatter bred they become,not only making it uncertain of colour, stamp,etc, but also uncertain of working ability, thats why the likes of Nuttall,Chapman,Mouseley,etc all went back to basics when starting a line,years ago there were only a handful of breeders specialising in one type, i.e.: Patts,Russells,etc and if you were after a guaranteed worker providing you had the dosh they would sell you one, whereas now there are loads of wannabes that are putting worker / worker as you say but still producing