Sir Quentin Thomas retires from BBFC after 10 years
The British Board of Film Classification (BBFC) is seeking a new president after Sir Quentin Thomas announced that he is to retire.
Sir Quentin, who has held the position for 10 years, described his time in charge as a "great privilege".
"When I was appointed, Ali G said it was the best job in the world as you got to watch porn all day.
"He was wrong about the porn but right that it is a great job." Sir Quentin will stay until a successor is chosen.
He added the position had provided him with "ample opportunity to sample the range, depth and diversity of film."
Prior to becoming BBFC president, Sir Quentin held posts at the Home Office, the Northern Ireland Office and the Cabinet Office.
He also worked on the law on obscenity and film censorship and advised the government on broadcast policy during his time at the Home Office.
"It has been a great privilege and pleasure to serve as President," said Sir Quentin in a statement.
"The Board has a great team under the effective leadership of its Director David Cooke. There is an enthusiastic staff with an unrivalled knowledge of film and of the regulatory issues."
During the last 10 years, Sir Quentin has presided over a number of controversial classifications.
The board defended its decision, in 2008, to award The Dark Knight a 12A certificate after getting more than 80 complaints about the Batman film's disturbing content.
In 2010, the board received 24 objections over its decision to give Peter Jackson's film The Lovely Bones a 12A rating - more complaints about than any other movie that year.
The BBFC celebrated its 100th year last month, with a book charting 100 years of classification scheduled for the autumn.
"I hope and believe the public and the industry appreciate the work the Board has done now for some 100 years," added Sir Quentin.
"It is important we retain their confidence as film continues to explore the full range of human experience, inevitably pushing at the boundaries as it does so."
Director of the BBFC, David Cooke, said the outgoing president's tenure had brought greater public interest and respect from within the industry.
"I am very sorry that we have been unable to persuade Sir Quentin to stay on." he said.
"He has overseen improved efficiency and speed of decisions, innovative new services for video-on-demand, and the provision of rich and helpful content information to the public."
The appointment process has already begun to choose Sir Quentin's successor.