John Martin to take over running of Turner Broadcasting System Phil Kent, head of Turner Broadcasting System for more than a decade, will hand over the running of Time Warner's largest division next year to John Martin, the media group's chief financial officer. The news, announced on Wednesday, marks the latest shake-up to Time Warner's senior ranks and puts Mr Martin in a high-profile operational role four years before the expiry of Jeff Bewkes" contract as chairman and chief executive. A three-way succession battle at the group's Warner Bros studio, home to Pacific Rim and the Batman films, ended with Mr Bewkes appointing Kevin Tsujihara in January. Last September he elevated Richard Plepler to be CEO of HBO, the premium channel operator behind Game of Thrones and The Newsroom. Mr Martin's move could also affect Mr Bewkes" attempts to find a new CEO for Time Inc, the publisher of magazines such as Time, People and Sports Illustrated which Time Warner plans to spin off within the year. Howard Averill, Time Inc's chief financial officer and an internal candidate to run the magazine company, could instead succeed Mr Martin, two people close to the company said. Such a move would raise the prospects of Mr Bewkes choosing an external candidate such as Michael Klingensmith, who was reported earlier this month to be a front-runner. Mr Klingensmith, who now runs the publisher of the Minneapolis Star Tribune, worked at Time Inc from 1976 to 2008. A third person close to Time Warner said an announcement on the Time Inc succession looked likely this summer, but cautioned that the group was still looking at about four internal and external candidates. Mr Kent will stay on as chairman of the business founded by Ted Turner for an handover period next year. Mr Martin's appointment will put him in charge of a global portfolio of cable, satellite and free-to-air channels, from CNN, TNT and Cartoon Network in the US to international networks such as Chilevision. The Turner portfolio has been one of Time Warner's strongest-performing divisions, pursuing international growth in Latin America, Europe and beyond while benefiting from rising revenues for the US cable network industry. Spin-offs under Mr Bewkes of divisions including AOL, Time Warner Cable and now Time Inc have left the group focused on television and film.