Do you know, Mr. Cook, the creator of Orpingtons knew that. In his book "Fowl for the times" I think it was, he recommended crossing his Orpingtons with other breeds for superior egg laying. Maybe those Aussies read that book and started crossing? No idea. I always find history interesting though.they based australorps on the old black orpington , thats a head scratcher thou..cant figure out how they knew that such a poor egg layer crossed with this and that could produce record holders...yet it worked..i know when you start crossing birds production goes up..but never dreamed blk orp would figure into that..