Stephen Carter, the chief executive of telecoms and media regulator Ofcom, announced his resignation on Friday morning.
Carter, the former head of NTL, joined Ofcom on its formation in 2003, when five regulators were combined into a single watchdog for the communications sector.
There is no word yet on his successor, but many believe that Ed Richards, Ofcom's current chief operating officer and a former policy advisor to Downing Street, is in the running.
Luke Gibbs of OfcomWatch told ZDNet UK that Richards "looks a shoo-in", but added: "There will be a few eyebrows raised in the political world if an independent regulator appoints someone so close to the government.
"He's previously worked at both Number 10 and Number 11. In a rapidly changing political climate, Ofcom will need to tread carefully," Gibbs said.
The search for Carter's replacement officially begins in June, when the post will be advertised nationally. A spokesperson for Ofcom told ZDNet UK that "continuity and an orderly transition" to the next chief executive would be aided by the fact that the body's chairman, Lord Currie, was recently reappointed until 2009.
The package that Carter will take with him is currently unclear, although his salary was listed in Ofcom's 2004-2005 annual report as being £414,463. He has previously taken flak for the levels of both his Ofcom salary and the package he took with him from NTL, which included $2.6m (£1.4m) in bonuses, despite what was viewed by many as a poor performance at the helm.
It is also not yet clear as to where Carter will be going, as the terms of his contract forbade him from seeking further employment while at Ofcom. He will be stepping down from his post in October, and some have speculated he will return to a board position at WPP, the communications group where he served prior to joining NTL.
Ben Verwaayen, the chief executive of BT Group, told ZDNet UK that Carter had changed the landscape of telecommunications regulation in Britain.
"His commercial experience, judgement and professionalism have been fundamental in helping to give Britain the most competitive and innovative telecoms market in the world. He has helped focus regulation on the parts of the market that need it, allowing greater competition to flourish," said Verwaayen.
One part of the market in need of attention was BT itself, which split off its access services division to form Openreach in 2005. The move followed an Ofcom review of the UK's telecoms sector, which forced BT to open up its network to rival operators on fairer terms.