CONOR Cruise O'Brien's life straddled diplomacy, politics, historical scholarship, literature and journalism. He was a diplomat at the UN, a professor in the US, a government minister in Ireland, the Editor-in-Chief of 'The Observer' Sunday newspaper in Britain and a writer whose work commanded attention throughout the English-speaking world.

He was an inveterate controversialist, the quality of whose judgment and the wisdom of whose actions were often questioned. But none could deny the force of his intellect, the skill of his exposition and the courage with which he held to his convictions.

He was born in 1917 into a family caught up in the heady political and literary life of Dublin. His mother Katherine, daughter of the Irish Party MP David Sheehy, was probably the original of Miss Ivors, a strident nationalist girl depicted in James Joyce's short story The Dead. His father, Francis Cruise O'Brien, was a somewhat waspish journalist who disconcerted his associates by abandoning his religion and speaking with an Oxford accent. He died suddenly in Conor's presence on Christmas Day 1927.

Pressure

Despite pressure from priests and some of her family, O'Brien's mother conformed to her agnostic husband's wish that their son should not be sent to a Catholic school. Friends, among them Joyce, clubbed together to find the fees to send him to Sandford Park, a non-denominational school where his cousin, Owen Sheehy-Skeffington, was head boy. From there the young O'Brien went on to the then predominantly Protestant Trinity College.

The result was that he was educated in a minority culture, apart from the mainstream of Catholic Ireland. His accent was different. He was to remain an outsider in Irish life, widely perceived as having the superior attitude to his compatriots associated in many minds with Trinity and the Protestant Ascendancy.

At Trinity O'Brien read Irish and French before turning to history, and made a clean sweep of the prizes. He took his first steps in journalism as college correspondent of The Irish Times. He also joined the Labour Party -- and then embarrassed it by his outspoken opposition to Franco in Spain.

Before he left Trinity he married Christine Foster, a fellow-student who was a member of a noted liberal Protestant family in the North.

In 1944 he entered the Department of External Affairs, as the diplomatic service was described. In the late 1940s and early 1950s he was employed on a virulent anti-partition campaign launched by the Foreign Minister, Sean MacBride, and universally supported by Irish political leaders. This denied the right of the majority in Northern Ireland to opt out of the Republic. O'Brien ran the Irish News Agency, which turned out propaganda. For all his later protestations, there is no evidence that he was other than enthusiastic about the policies he helped to propound.

In 1952, under the pen-name Donat O'Donnell, he published a book, Maria Cross, a series of essays on Catholic writers including Albert Camus, Graham Greene and Evelyn Waugh. At this time he was also engaged on a study of Charles Stewart Parnell, for which he was awarded a doctorate. Published in 1956, it placed him in the front rank of Irish historians.

After a stint at the Paris embassy in the mid-1950s, O'Brien was appointed head of the UN section of the Department of External Affairs. Ireland had just been admitted to membership of the UN. The Foreign Minister, Frank Aiken, rejected suggestions that Ireland should align itself totally with the US and its Western allies. This was manifested in a decision to vote in favour of discussing the admission of Communist China to the UN. O'Brien believed that Ireland should model its approach on that of neutral Sweden, and did not hide his conviction that imperialism was a greater evil than communist movements in the developing world.

Dag Hammerskjold, the Swede who was Secretary-General of the UN, had observed O'Brien closely and read Maria Cross. As a result, the Irish Government was requested to second O'Brien to serve with the UN in the Congo, where civil war had broken out after the country became independent of Belgium. Although a UN resolution had stated that force was to be used in the last resort to remove from Katanga the foreign mercenaries who were assisting the secessionist regime of Moise Tshombe, O'Brien was reviled as unnecessarily pugnacious when he authorised such force.

Belgium and Britain had an interest in maintaining a compliant regime in mineral-rich Katanga. Under pressure from the Western powers, Hammarskjold sought a compromise and was on the way to negotiate with Tshombe when he was killed in a plane crash. After his death it was impossible for O'Brien to establish definitively that he had acted within his remit, and he was recalled to New York and relieved of his post.

By this time O'Brien's marriage had broken down, his wife complaining that it was impossible to go on living with a man who thought he was God. O'Brien had formed an attachment to a colleague in the Department of Foreign Affairs, Maire Mac an tSaoi, whose father was Tanaiste. The affair was made public by the British press when Mac an tSaoi appeared in the Congo at the height of the crisis. This was used as a stick to beat O'Brien in the UN, and it embarrassed the Government. Mac an tSaoi resigned from the diplomatic service, and after O'Brien's divorce in Mexico, they were married in New York. Leaders of the emerging African nations admired O'Brien's stand against the colonial nations in the Congo.

In 1962 Kwame Nkrumah, President of Ghana, invited him to become Vice-Chancellor of the newly created University of Ghana. Relations went sour, however, little over a year after O'Brien took up the appointment, when he protested publicly against the dismissal of the Chief Justice who had acquitted some of the president's political opponents.

They parted by mutual consent at the end of the three-year term. The O'Briens maintained their connection with Ghana by later adopting a boy of mixed Irish-Ghanaian parentage. They also adopted a half-African daughter.

From 1965 to 1969 O'Brien was Albert Schweitzer Professor of Humanities at New York University. O'Brien had returned to Ireland in 1969, when he was invited by the Labour Party to contest a seat in the Dail. He was successful and became the party's spokesman on Northern Ireland. However, when the IRA began its campaign of violence, he came to argue that the root of the problem lay in the Republic's claim of right to Northern Ireland irrespective of the wishes of its inhabitants.

In his book 'States of Ireland' (1972) he challenged the nationalist dogma that Ireland was one nation. Ultimately this reshaped Irish attitudes, but at the time it raised doubts about O'Brien's nationalist credentials.

As a minister in Liam Cosgrave's coalition government formed in 1973, O'Brien urged his colleagues to settle for power-sharing in Northern Ireland. His advice was not heeded, and provision was made for a potentially powerful council in the Sunningdale agreement.

But like many prophets of doom, O'Brien was not held in any esteem for his prescience among those to whom his warnings were directed. He fell foul of the media when, as Minister for Posts and Telegraphs, he forbade television interviews with supporters of Sinn Fein.In the 1977 general election the Government of which 'the Cruiser' was a member was heavily defeated, and he lost his Dublin seat. He was fortunate when he was recommended to the new American owners of 'The Observer' as an Editor-in-Chief by David Astor and also by his old adversary, Harold Macmillan, who said the paper needed another J L Garvin. At his best O'Brien was a brilliant columnist, concise, witty and always easy to read. He was retired as Editor-in-Chief in 1981 but wrote a weekly column until 1984.

O'Brien continued his work unabated from his home in Howth near Dublin.

He continued to be a scourge of republicans and their fellow-travellers at home, whether in his columns in the 'Irish Times', 'The Irish Independent' or in 'The Sunday Independent', to which he became a regular contributor. His favourite target was Charles Haughey. His unexplained wealth, his arrogance and association with the illegal importation of arms in 1970 made him a good target. But O'Brien did not know when to stop and, in the absence of proof, the campaign deteriorated into a vendetta; Haughey, who did not deign to reply, sailed on regardless to be exposed only after he had retired.

He foresaw that the IRA ceasefire of 1994 would not hold and insisted that communal warfare would be the inevitable outcome of any effort under the Downing Street declaration of the previous year to foist all-Ireland institutions on Ulster Unionists.

This led him to join Bob McCartney's UK Unionist Party, which was free from the sectarian overtones of other unionist parties and favoured closer integration with Britain. As such he served in 1996 on the Northern Ireland Forum, which was to lay the groundwork for the Good Friday Agreement of 1998.

Although there was some special pleading and much repetition of his old themes in his memoirs, the book afforded an insight into the roots of the personal insecurity and vulnerability behind the self-assurance that so often came over as arrogance.

He is survived by his wife Maire, a poet, their two adopted children and also a son and daughter from his first marriage. Kate Cruise O'Brien, a daughter also from his first marriage, died in 1998.

Conor Cruise O'Brien, politician and writer, was born on November 4, 1917. He died on December 18, 2008, aged 91.