Conor Cruise O'Brien was the pre-eminent Irish intellectual of his generation (and a few others). In his numerous books and essays, profound reflections and an astonishing range of cultural references were expressed in a lapidary style, replete with implications and often horribly funny. He could be uproariously good company, in every sense. If he was a great faller-out with political colleagues, his enduring friendships spanned an unlikely and distinguished spectrum. But he also aroused controversy throughout his diplomatic career in the 1950s and 1960s, at the UN and in Africa, and drew down the wrath of the Church for one kind of defection or another. He eventually decided, though, that given the choice of Cathleen Ni Houlihan or Holy Mother Church, he would choose "Holy Mother Church, every time". And above all it was his recantation of the pieties of Irish nationalism in the early 1970s, and his repeated inquiries about where the Ulster Unionist presence fitted in to the traditional Irish shibboleth of "reunification", that conferred demonic status on him in the eyes of "official Ireland".

Venial sins of "arrogance" and "opportunism" were also imputed. But the major transgression was to say the unsayable, in a simple and memorable way. "The official ideology of the Republic fully legitimises the IRA's ‘war' in Northern Ireland and so helps that ‘war' go on and on," O'Brien wrote in the New York Review of Books in 1982. "The people of the Republic do not endorse that ‘war', very far from it...But our history, our ‘idealistic' pretensions and our fatal ambivalence have stuck us with an ideology that is warlike and anti-demo-cratic, and calls increasingly for further human sacrifice. Our ideology, in relation to what we are and want, is a lie. It is a lie that clings to us and burns, like the shirt of Nessus."

By the time of that New Yorker inquiry, even Sinn Féin were moving towards an acceptance that their war of liberation had been largely built on wishful thinking, at the cost of thousands of deaths. The diplomatic ballet of the next few years would choreograph a structure within which they could climb down and come to rest as ministers of a local power-sharing government of the kind that they had fought against when it was floated decades before, by the short-lived Sunningdale arrangement of 1973-4. O'Brien had been a government minister at that time, and a signatory of the Agreement, but felt that its imposition of an overarching Council of Ireland would alienate Unionist support - as it did. He knew that the Northern republicans, in their current mood, would never allow a chance to a cross-party devolved government, in which their moderate-nationalist enemies the SDLP were strongly represented, if they could help it. (As it happened, Ulster Workers' Council bully-boys and pusillanimous Labour politicians did most of their job for them.) Twenty-five years after the negotiations at Sunningdale, the Good Friday agreement reran the formula, with Sinn Féin participation (and the concomitant effect of administering a dose of euthanasia to the SDLP). By then, O'Brien's hostility to everything about republicanism was so dyspeptic that he could hardly countenance the idea of them in any kind of position of power at all. But they, like everyone else, had been in an odd way his pupils.