Cedric Thornberry obituary

Cedric Thornberry, who has died aged 77, always looked for ways of using his skills as a lawyer to make the world a better place. When I first knew him, it was for pioneering the teaching of international human rights law at the London School of Economics and for the interest he had taken in Namibia. From 1978 onwards I was the special representative of the secretary general for that country, and had arranged for Cedric to work with me. We wanted to open international negotiations and establish a UN presence there in order to release the former South West Africa from the administrative control that South Africa had held over it since the time of the first world war.

After initial exchanges proved fruitless, Cedric served the UN in Cyprus, the Middle East and New York. In the late 1980s, as the question of Namibia returned to the forefront of the UN's agenda, he again joined me in New York for the organisation of the United Nations Transition Assistance Group (UNTAG). The UNTAG mission supervised and controlled elections in Namibia in 1989, and independence came the following year.

As director general of UNTAG, Cedric saw the inclusion of women as essential. Not only was the mission widely seen as successful in keeping the peace, but also in doing so through an unprecedented degree of gender balance.

By 1992, Cedric was in the Balkans. As head of the non-military side of the UN's peace operation, he persuaded Serbian forces to hand over Sarajevo airport for what became the UN's largest humanitarian airlift. This eventually became a factor in the lifting of the siege of the southern city of Mostar. Cedric's wide knowledge and experience, and his abilities as negotiator, communicator and organiser made a key difference to the UN's efforts in resolving international conflicts.

Born in Belfast, Cedric came from a family with strong roots in the Northern Irish counties of Tyrone and Fermanagh. He was the eldest of two sons of Lila (nee Watson) and her husband Laylee, the headteacher of Lurgan Model primary school, Co Armagh, and a president of the Ulster Teachers' Union. Cedric attended Finaghy primary school, Belfast, and then Methodist College, where he was active in drama and sport.

In 1954 he went to St Catharine's College, Cambridge, on an exhibition to read law. He followed his BA with an LLB in international law, and was called to the bar in 1959. From 1958 he wrote on and taught international and constitutional law at Cambridge, and in 1960 moved to the LSE.

He was briefly tempted into politics and stood for Labour, but even in Harold Wilson's landslide election victory of 1966 Guildford remained Conservative. Thereafter he devoted his considerable energy to making international law and eventually international peace-keeping more effective.

Cedric greatly admired Wilson's lord chancellor, Lord (Gerald) Gardiner, and worked with him in the late 1960s and early 70s, particularly in relation to Northern Ireland and the conditions of detention of political prisoners. Cedric was one of the founders of the civil rights movement in Northern Ireland.

At that time he also acted as counsel to individual applicants to the European court of human rights. Among the many cases he pleaded in Strasbourg, the best remembered is one from 1978 in which a birching on the Isle of Man was found to constitute a degrading punishment.

Cedric's association with the Irish politician Seán MacBride, a founding member of Amnesty International, took him to Greece after the military junta seized power in 1967. Later, in 1973-74, he went to Windhoek, the Namibian capital, to monitor the political trials of members of Swapo (South West Africa People's Organisation).

By the time Cedric left the UN in 1995, he was an assistant secretary general. He pursued his activities as lecturer and consultant on peacekeeping and human rights matters, notably as a visiting professor at the Centre for Defence Studies at King's College London.

Cedric was married and divorced four times. He is survived by five children: Emily, James, Benjamin, Caitriana and Eilise Marie; another son, Peter, died in 2011. He is also survived by four grandsons and two granddaughters.