Jyoti Basu came within a whisker of becoming India's first ever Communist Prime Minister.
But it was his own party that scuppered his chances, a decision he later denounced as a historic blunder.
Jyotirindra Basu was born into a middle class Bengali family in Calcutta on 8 Jul 1914. His father was a doctor who had originally come from East Bengal, now Bangladesh.
He had a privileged childhood, studying in one of Calcutta's Catholic schools and the prestigious St Xaviers college before graduating from Presidency College in 1935.
As a student, Mr Basu led his friends on a daytime raid of a whites-only club in Calcutta, splashing in its swimming pool until they were fished out.
He moved to London where he studied for the bar and became involved with the Communist Party of Great Britain before returning to India where he worked full time for the Indian Communist Party.
In 1944, encouraged by his party, Mr Basu became involved with the railway unions in India, eventually becoming general secretary of a new combined union.
This led to his election to the Bengal legislative assembly in 1946. In 1957, he became leader of the opposition in the West Bengal assembly.
Mr Basu was appointed home minister in West Bengal's first Left dominated United Front government in 1967 but the coalition was brought down and central rule imposed after Bengal was rocked by a huge wave of Maoist violence.
But when the Left coalition came to power in 1977 with a much more comfortable margin, Jyoti Basu was unanimous choice as chief minister, a post he held until 2000.
His government was credited with restoring political stability and bringing in land reforms which gave poor farmers an opportunity to have their own holdings.
However, he was also accused of failing to stand up to powerful trade unions which resisted his attempts to bring in foreign investment and rejuvenate local industry.
His opportunity to become prime minister came in 1996 when a federal coalition was cobbled together by some Left, lower caste and regional parties.
Many felt that his long experience in holding together a Left coalition in Bengal would be invaluable in controlling an often fractious grouping at federal level.
But Mr Basu's party, the Communist Party of India (Marxist) decided to support the coalition from outside and not join the government.
Some commentators believed that if he had become prime minister it might well have prevented the Hindu nationalist Bharatiya Janata Party from coming to power.
Often described as a Fabian Socialist rather than an orthodox Communist, Jyoti Basu worked by consensus, successfully managing coalitions, while showing a healthy respect for the viewpoints of others.
"He made Communism look respectable," according to Sabyasachi Basu Roy Choudhuri, a Calcutta-based political analyst.
Analyst Ashis Chakrabarti said Mr Basu's success indicated social democracy had a future that Communism did not .