Senior Labour backbencher Sir Stuart Bell died this morning after a short battle with pancreatic cancer, his family said.
The 74-year-old had been MP for Middlesbrough for nearly three decades, and served in key positions in Parliament.
Sir Stuart was the son of a Durham miner, and, after a grammar school education, was briefly a colliery clerk and newspaper reporter before becoming a barrister.
The death of Sir Stuart Bell is a "huge blow", Labour leader Ed Miliband said as he lead tributes to the veteran Labour MP.
"Sir Stuart's death will come as a huge blow to his family and many friends and colleagues," Mr Miliband said as MPs from all sides saluted his courtesy and kindness.
Having lived and worked in Paris for a spell, he returned in 1977 to pursue a career in politics.
He unsuccessfully contested Hexham in 1979, and was a member of Newcastle City Council until he won Middlesbrough in 1983. He went on to hold the seat through seven general elections.
While never serving as a minister, Sir Stuart was the party's Northern Ireland spokesman during the 1980s.
And later in his career he was handed a powerful role on the Commons Commission - the body responsible for running the House.
He played a central role during one of Parliament's most difficult periods, as the long-running scandal of MPs' expenses abuses finally emerged in 2009.
Sir Stuart, who had been suffering pancreatic cancer, died at home with his family around him.
Senior Labour figures such as Chris Bryant and Chuka Umunna expressed their sadness at his death.
Former prime minister Gordon Brown later added his tribute.
He said: "Sir Stuart Bell combined great expertise with sound judgment.
"He will be remembered for his commitment to Middlesbrough as a constituency MP and for his great enthusiasm for social justice, Europe and the best relations between church and state, where his contribution will never be forgotten.
"My thoughts are with Stuart's family."
Prime Minister David Cameron said Sir Stuart was "one of Parliament's great characters".
"Throughout his three decades in the House of Commons, he always stood up for those issues he cared most deeply about," he said.
"A firm advocate of church matters as Second Church Estates Commissioner for 13 years, and a member of the House of Commons Commission over a very challenging decade, he will be remembered for his kindness and his courtesy towards Parliamentary colleagues.
"My thoughts go out to Stuart's wife, Margaret, and his family at this very sad time."