Tony Benn, the stalwart of the British left who spearheaded the movement against the Iraq war, has died at the age of 88, his family says.
A Labour cabinet minister in the 1960s and 1970s, Benn was a widely respected orator who often clashed with his party when it drifted away from the socialism he espoused.
Benn also forced a change in the law allowing the aristocracy to renounce their titles, after he was forced to give up his seat in the House of Commons when he inherited his father's Viscount Stansgate title in 1960.
"It is with great sadness that we announce that our father Tony Benn died peacefully early this morning at his home in west London surrounded by his family," said a statement from his children Stephen, Hilary, Melissa and Joshua.
They thanked the health workers who looked after him both in hospital and at home.
"We will miss above all his love which has sustained us throughout our lives. But we are comforted by the memory of his long, full and inspiring life and so proud of his devotion to helping others as he sought to change the world for the better."
Prime Minister David Cameron said he was sorry to hear of Benn's death and paid tribute to him.
"He was a magnificent writer, speaker, diarist and campaigner, with a strong record of public and political service. There was never a dull moment listening to him, even when you disagreed with everything he said," Cameron said in a statement.
Labour leader Ed Miliband, who got an early taste of politics doing work experience with Benn aged 16, paid tribute to an "iconic figure of our age".
He said: "He will be remembered as a champion of the powerless, a great parliamentarian and a conviction politician.
"For someone of such strong views, often at odds with his party, he won respect from across the political spectrum.
"This was because of his unshakeable beliefs and his abiding determination that power and the powerful should be held to account."
He said that when he was a teenager, Benn was "incredibly kind" and treated him as an equal.
"I saw him for the last time a couple of weeks ago in hospital. He may have been ailing in body but was as sharp as ever in mind. As I left he said to me `Well, old son. Let's have a proper talk when you have more time'."
Former Labour prime minister Gordon Brown said: "Tony Benn was a powerful, fearless, relentless advocate for social justice and people's rights whose writing as well as speeches will continue to have a profound influence on generations to come."
Benn's wife Caroline died in 2000 from cancer.
His son Hilary Benn is a Labour MP who has served as international development and environment secretary.
