Ladbrokes had put Cox in the betting as a rank outsider at 25/1 as it is revealed that the former LWT man has applied for the job.
Cox is a former adversary of the previous director-general Greg Dyke and it is understood that they fell out with each other when they worked together at LWT. He comes as a surprise contender having served on a committee to recommend the phasing out of the licence fee earlier this year. He is currently a writer and broadcaster.
Punters still want to back Mark Thompson, despite declaring himself out of the race. His odds have been cut from 5/1 to 7/2.
Byford comes in as favourite at 7/4, while the BBC's director of television Jana Bennett and Sky Networks managing director Dawn Airey come in at an equal 5/1. The BBC's head of radio Jenny Abramsky is currently coming in at 8/1.
Other contenders are United Productions chief executive John Willis at 16/1, former Channel 4 chief executive Michael Jackson at 16/1, BBC Worldwide chief executive Rupert Gavin at 20/1, and former chief executive of Granada Content Simon Shaps at 25/1.
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