The chair of the BBC Trust, Lord Patten, is resigning from his position immediately on health grounds after undergoing major heart surgery.
The former Conservative minister was admitted to hospital at the end of April with severe chest pains before having a combination of bypass surgery and an angioplasty.
In a statement Lord Patten said his doctors had advised him to "reduce the range of roles" he takes on.
On stepping down from the BBC Trust, he said:
"This is a position that requires and has received from me 100 per cent commitment, and has been my priority at all times.
"It would not be fair to my family to continue as before; and equally it would not be fair to the BBC and those it serves not to be able to give that commitment which the role demands."
Ukip leader Nigel Farage has defended Top Gear presenter Jeremy Clarkson over the n-word row, saying it was "typical" of the BBC broadcaster.
Asked about the Clarkson row Mr Farage said: "The more controversial Jeremy Clarkson is, the more people watch his programme, and the more money the BBC makes out of marketing a show that sells globally and makes them a fortune.
"I would think it's just typical Clarkson, getting very, very close to the line of being offensive but perhaps not quite going over it," he said.
Mr Farage made the comments as he launched Ukip's billboard campaign for the Euro-elections against the backdrop of the cliffs of Dover.
Jeremy Clarkson has attacked his employers at the BBC for urging him to apologise following claims he used racist language and said he is on his final warning from the broadcaster.
The Daily Mirror claimed that during the filming of Top Gear, the presenter used the N-word while reciting nursery rhyme Eeny, Meeny, Miny Moe. The paper posted the unaired footage of the possible racist rhyme on its website.
Writing in his weekly Sun column, Clarkson said: I've been told by the BBC that if I make one more offensive remark, anywhere, at any time, I will be sacked.
"And even the angel Gabriel would struggle to survive with that hanging over his head.
"It's inevitable that one day, someone, somewhere will say that I've offended them, and that will be that."
He added: "But saying sorry for using the most racist word of them all and hoping the story would die down as a result?
"...It's something I hadn't done."
Deputy Labour leader Harriet Harman has called for the BBC to sack Top Gear presenter Jeremy Clarkson over the use of the N-word.
The shadow culture secretary said anybody who used the word "in whatever context" should have no place at the broadcaster.
Anybody who uses the N-word in public or private in whatever context has no place in the British Broadcasting Corporation.
Her intervention came after Education Secretary Michael Gove urged the corporation not to axe Clarkson.
Singer Jamelia has called for the BBC to sack Jeremy Clarkson following allegations he used racist language whilst filming Top Gear.
Talking on the Loose Women chat show today, she told her fellow panellists: "Personally, I believe the BBC should exercise zero tolerance. He has got to go.
"He is in a position of power and influence and there are so many people of many different races who watch his shows and that should not be in your vocabulary, it should not be in your head."
"As a black woman I am offended when I hear it anywhere," the Superstar singer said.
Speaking about a possible racist rhyme sung by Jeremy Clarkson during a Top Gear recording, British writer, radio and television presenter Paul Merton has said that:
"Even under your breath or as a joke, I don't think it is appropriate."
British radio and television presenter Clive Anderson has said that Jeremy Clarkson was "ill advised" to say a possible racist rhyme during a Top Gear recording.
He continued by saying the rhyme was "used casually" in the past and is unsure whether looking at Top Gear outtakes is a way to "asses Clarkson's contribution to the nation."
The Education Secretary Michael Gove has said an alleged racist word used by Jeremy Clarkson during filming of a Top Gear episode was "horrendous and shouldn't be used," but said the apology from the presenter should be enough.
Speaking to ITV's Good Morning Britain he said: "It seems to me this is a word he never intended to mutter or broadcast.
"He has been clear in his apology and we should leave matters there."
Controversial Top Gear presenter Jeremy Clarkson is "running out" of apologies and should step down from the publicly funded BBC, a Labour MP has told Good Morning Britain.
Jim Sheridan, who sits on the Culture, Media and Sports Committee, has written to the BBC to demand Clarkson's resignation after he was filmed allegedly using the n-word.
"The BBC is funded by the taxpayer. And I don't think the taxpayer should be subjected to people like Jeremy Clarkson, who uses and insults people by his comments. So it is time for him to go."
Top Gear presenter Jeremy Clarkson has told The Sun newspaper that he "wishes to God" that his attempts to cover up a racist word during filming for Top Gear had been better.
Clarkson has become embroiled in a public racism row following claims that he has used the n-word while reciting a rhyme.
I wish to God that my attempts to cover up that word were better than they were.
I was simply mumbling - saying 'ner ner' or something similar, anything but the N-word.
It was my mistake and I apologise for not covering it up.
But if you look at the footage you can see what I'm trying to do.
I've racked my brains to think if there is another way to do it without doing eenie, meenie, miny, mo. It was a good hour.
What we did was entirely innocent. I would invite my readers to tell me of an alternative.
The segment was later edited out of the BBC broadcast.