Channel 4's controller of legal and compliance Jan Tomalin has quit after 20 years at the station to start up her own legal practice.
Tomalin joined Channel 4's legal team as a newly qualified lawyer in 1988 and has headed the team since 1992. During her time at Channel 4, Tomalin helped defend a number of controversial broadcasts, including Brass Eye's paedophile special.
Tomalin said: "I'll miss my friends here but they know that my real passion is for working hands-on with creative teams and I'm very excited about having the opportunity to do this within my own legal consultancy."
Channel 4's director of television and content Kevin Lygo said: "Her commitment to freedom of expression is unwavering and she has been absolutely crucial in shaping the channel's output for the last 20 years."
Channel 4 said it would announce a replacement for Tomalin "in due course".