Lord Longford: Willing to fight the fight
Aged 95, he came in for repeated stern criticism by the public and press for his campaign to secure the release of celebrated criminals, in particular Moors murderer Myra Hindley.
He once described Hindley as a "delightful" person and argued that you could loathe what people did but not what they were.
"It was a great life and he was a great man."
Prime Minister Tony Blair, who heard of Lord Longford's death while in Mexico, said he was "a man of passionate integrity and humanity and a great reformer committed to modernising the law while also caring deeply for individuals".
Born on 5 December 1905 the second son of the fifth Earl of Longford, Frank Pakenham was educated at Eton and Oxford.
Conversion
At 25 he joined the Conservative Party but his future wife, Elizabeth, who he had met at Oxford, persuaded him to become a socialist and convert to Roman Catholicism from Protestantism.
The couple had eight children together.
His first cabinet post came under Harold Wilson as Lord Privy Seal and leader of the House of Lords.
An active social worker, he was chairman of the National Society for Physically Handicapped Children, chairman of Mencap and of the National Youth Employment Council.
He also presided over various inquiries relating to crime and punishment and the re-habilitation of ex-prisoners.
Frances Crook, of the Howard League for Penal Reform, said Lord Longford was always willing to challenge people and generate debate.
"I always assumed he was going to be around to fight the fight that no-one else has the courage to fight," she told BBC News 24.
'Kindly and thoughtful'
She said Lord Longford's dedication to penal reform went back almost 50 years.
"He was one of the most important proponents of that debate."
Former Labour MP Tony Benn, who served in Harold Wilson's government with Lord Longford from 1964-68, remembered the peer as a "kindly and thoughtful" man.
He said the controversy over his support for Hindley should not be allowed to overshadow memories of his pre-war opposition to the appeasement of Hitler and his work on the Beveridge reforms which led to the creation of the welfare state.
The leader of Roman Catholics in England and Wales, Cardinal Cormac Murphy-O'Connor, the Archbishop of Westminster, paid tribute to Lord Longford's loyalty to his faith.
"He was an outstanding Christian witness who devoted his entire life to the Catholic faith. May he rest in peace."