SYDNEY — The rapid Australian ascension of the 25-year-old Lachlan Murdoch was completed Thursday, with his appointment to the chairmanship of News Ltd., the Oz subsid of News Corp. Rupert Murdoch’s son adds the chairmanship to his News Ltd. managing directorship, which he held since September.Since the 61-year-old Ken Cowley, a 33-year News Corp. vet, said he would retire July 1 from executive chairmanship of News Ltd., it has been expected that Lachlan would assume unfettered control of News Corp.’s $3.5 billion worth of Oz assets (Daily Variety, April 16). News Ltd., with holdings in newspapers, TV, sports, feevee, magazines, record labels and an airline, is practically a microcosm of News Corp. globally. In less than three years, the London-born, U.S. naturalized Princeton philosophy graduate has rocketed through the ranks from his first post as general manager of regional publisher Queensland Press. Lachlan is the only Murdoch scion to sit on the executive board of News Corp. He is also deputy chairman of News Corp.’s Hong Kong-based Asian satcaster Star TV.