On 1 November 2018 Lachlan Murdoch, the eldest son of the media tycoon Rupert Murdoch, made a rare public appearance at a New York Times DealBook conference. Dressed in a sharp blue suit and open-necked white shirt, he looked relaxed and on top of the world. He had just been named chief executive and chairman of Fox’s TV businesses, while his brother James, a possible rival for the top job, was heading for the company exit. Lachlan was finally emerging as his father’s sole and undisputed heir. Not that everything was plain sailing at the Fox ship. A few days...