By Priyath Liyanage
Editor, BBC Sinhala service
Anton Balasingham, whose death from cancer was announced on Thursday, was the ideologist of the Tamil Tigers of Sri Lanka.
Mr Balasingham's death is a loss to both sides
Officially know as the group's political adviser and theoretician, for over 25 years he played a unique role in the political struggle of Sri Lanka's Tamil minority.
Over the years, this normally reticent man was the public face of the Tamil Tigers. Living in London, it was his job to communicate with the outside world about the aspirations of his people.
He was the main force in bringing the attention of the world to a forgotten war in this small island nation.
Earlier in his life, Balasingham worked as a journalist in one of the Colombo newspapers before joining the British High Commission in Colombo as a translator.
Mr Balasingham could challenge the Tiger leadership
In his youth he was an activist of the left, before he came to London to study for his doctorate.
Many commentators believe Balasingham was the moderating force - always on the search for a political solution - within one of the most belligerent rebel organisations in the world.
He is known for his relentless attempts to bring the Tigers to the international negotiating arena. It was mainly due to his perseverance that the Tigers acquired a reputation as a progressive organisation among certain liberals in the west.
He was able to live in Britain even though his organisation is proscribed by the UK government.
For over a decade however, Balasingham was plagued with physical ailments. Apart from bile duct cancer, he suffered from chronic diabetes, motor neurone disease and acute kidney failure.
Balasingham (l) has represented the rebels in numerous peace talks
Despite these illnesses, however, he never stopped his persistent campaigning to extend the armed struggle to the political arena.
In his memoirs, he wrote how sceptical the Tiger leader, Prabhakaran, had been about the national leadership of Sri Lanka.
He described how he managed to persuade a reluctant leadership to engage in peace talks, arguing his point time and time again that this was the right course of action.
Although he was not a part of the delegation in the first round of talks of 1985 in Bhutan, he was the main adviser to the militants in the Tamil delegation. Subsequently, he was actively involved in peace negotiations with many governments in Colombo.
Balasingham represented the Tigers in many of these talks as the chief negotiator.
He accompanied Prabhakaran at almost every meeting held with Indian and Sri Lankan political leaders, where he played a double role as interpreter and as adviser to the reclusive Tiger supremo.
Both sides now appear to be on a war footing
Analysts who had studied the role of Balasingham within the organisation say his departure will create an irreplaceable void within the organisation.
"Balasingham was the only person in the organisation who addressed the leader as an equal. Prabhakaran respected him as a teacher or an elder. There is no one else who has got such influence over the leader any more," says senior Tamil journalist DBS Jeyaraj.
With such power and respect, Balasingham will be remembered as perhaps the only person able to criticise certain decisions of the Tiger leader who is revered - and feared - for his teachings and diktats.
"We respected him as a guru. All of us read his books. He motivated us for our struggle," says the Tiger's military spokesman Rasaiah Illantherian.
Balasingham's high profile in the West, and his knowledge of the politics of the outside world, were an asset for the Tiger leadership which has never had much exposure outside of South Asia.
His death will be a blow not only to the Tamil Tigers but also to many in the south of the country. He provided a thread of hope for a peaceful resolution to the seemingly intractable and escalating conflict of Sri Lanka.