Rupert Murdoch, the famed Australian media tycoon and owner of Fox and News Corp., is stepping back from the chairmanship of his empire. Lachlan Murdoch, his son, is now taking the helm as chairman. The World’s Carol Hills talks with Simon Potter, a professor of modern history at the University of Bristol, about the complicated family dynamics playing out in the move, and the dynasty’s sway over British conservative politics over the years.