O'Leary, Cornelius (1927–2006), political scientist and Roman catholic activist, was born 15 August 1927 in Churchtown, Newcastle West, Co. Limerick, elder of two sons of Michael O'Leary, a Department of Agriculture instructor/inspector, and his wife Mary (née Donworth). His family roots lay in west Cork; he was a grand-nephew of Fr John O'Leary, a Land League activist and parish priest of Clonakilty, and Daniel Cohalan (qv), the Irish-American politician judge, was an uncle by marriage. O'Leary's family had strong Fine Gael sympathies and detested Éamon de Valera (qv), but when O'Leary met de Valera he was considerably impressed by his intelligence and simplicity.
O'Leary was educated at Clongowes Wood College, where Fr Fergal McGrath, a Clongowes elder statesman who wrote extensively on John Henry Newman (qv) and education, was a mentor. O'Leary then spent a year studying for the catholic priesthood at Clonliffe seminary, Dublin. At the end of his first year he was asked to leave by the seminary; he was given no reason and assumed that he was simply part of a 'cull' to keep down the numbers of ordinands (a regular practice at the time). As Clonliffe students attended UCD for certain courses, O'Leary decided that encounters with former classmates might be embarrassing and therefore enrolled at UCC, where he was taught history by James Hogan (qv). He was deeply influenced by Hogan's specifically catholic version of philosophical history, that included academic territory which in a more specialised institution would have fallen under the heading of political science. In later years O'Leary liked to recall his pleasure at telling Hogan that W. H. Morris Jones, the LSE political scientist, based his famous article 'In defence of apathy: some doubts on the duty to vote' (Political Studies, ii (1954), 25–37) on remarks in Hogan's magnum opus, Election and representation (1945). Hogan's influence was reflected in the fact that O'Leary was one of the few academic commentators to support the 1959 constitutional referendum to replace proportional representation with the first-past-the-post electoral system (though O'Leary later changed his views on this as on many other matters). Always clubbable, O'Leary was as an undergraduate a founding member of the Irish University History Students' Association.
After graduation from UCC with first-class honours in history and Latin, O'Leary proceeded to Nuffield College, Oxford, where he was the first D.Phil. student supervised by David Butler on election studies. He was active in the Oxford University Conservative Association, where he made the acquaintance of Michael Heseltine; though in later life he developed strong Labour sympathies (partly in reaction against the educational and other policies of Margaret Thatcher, prime minister 1979–90), he always retained a strong respect for Heseltine's abilities. While revising his dissertation for publication between 1955 and 1960 (delayed by the loss on public transport of a nearly-completed text), he taught in both catholic and non-catholic secondary schools; this was a painful experience which he described as 'an astonishing and mutually educative experience for both teachers and taught' (Guardian, 12 October 2006). For much of this period he resided in a hostel run by Opus Dei (the catholic lay organisation); although he was not (at least in his later years) a member, he retained a deep admiration for Opus Dei; he had personal friends among its Irish members, regularly read the devotional works of its founder, Mgr Josemaria Escriva, and made it the principal legatee in his will.
The publication by the Clarendon Press in 1960 of O'Leary's The elimination of corrupt practices in British elections 1868–1911 established his academic reputation. This account of the development of election law in the later Victorian and Edwardian period long remained a standard work (though after his death it was criticised for insufficient use of local sources). It is an unashamedly whiggish celebration of the advance of higher standards in politics; throughout his life O'Leary kept on the wall of his residence a picture of Mr Justice Wills, whose decisions formed much of the material for the book. O'Leary provided informal advice in various election disputes, such as the controversies surrounding Anthony Wedgwood Benn's campaign for the right to relinquish his peerage, the succession to which was depriving him of the right to remain in the house of commons, and the SDLP's defence against an election petition disputing Dr Joe Hendron's 1992 election as member for West Belfast.
In 1960 QUB appointed him a lecturer in political science; shortly afterwards he supervised the first Ph.D. dissertation awarded by the department of politics, a study of Irish literary censorship by Michael Adams (1937–2009). He was held in high regard by those whom he supervised; Sidney Elliott, a fellow psephologist and later a colleague, recalled: 'If there was a piece of work you were doing which he was supervising, you were the most important person in the world. The encouragement he gave you was enormous' (Irish News, 9 September 2006). His abilities as a good talker with a wide range of interests were displayed in tutorials; he loved to hold court in the common room, where he would discourse fluently to friends from all disciplines. In 1979 he became one of the first Roman catholics to head a department at QUB; although he took considerable pride in some of the appointments made during his tenure, his administrative skills left much to be desired and a considerable burden fell on senior colleagues.
In the 1960s and 1970s he often appeared on television (usually in connection with election coverage). In retrospect he regretted that he had not spoken out on the discriminatory nature of the Stormont administration in the 1960s, and he later attempted to use his talents in the service of peace. In 1973 he published (with Ian Budge) Belfast: approach to crisis 1613–1970, a pioneering study of Belfast municipal politics and the city's sectarian divide. (In later life he tended to require collaborators to help in organising his vast fund of knowledge.)
Always a prolific writer of letters to the newspapers, O'Leary often commented on the Northern Ireland conflict. He was particularly proud of a confrontation with the 1916 veteran W. J. Brennan-Whitmore (qv), who lauded the Provisional IRA in letters to the Sunday Independent. In the early 1970s he placed his trust in John Hume; later in the decade he offered advice to the loyalist Ulster Defence Association on formulating their proposals for peace through Ulster independence. Believing himself in danger from paramilitaries, for a time he lived in rapid and frequent transit between boarding houses. His nearest approach to a permanent home was his brother John's house in Cork city, where he spent holidays.
O'Leary maintained strong contacts with the catholic church (in the 1970s he represented the diocese of Down and Connor on a short-lived advisory body). In the early 1980s, as vice-president of the pro-life amendment campaign, he actively lobbied for an amendment to the Irish constitution precluding the legalisation of abortion. Some observers felt that as a somewhat unworldly bachelor he acquitted himself badly in public debates with feminists. He was, however, a prolific contributor to the letters columns of Irish newspapers on the subject and put his considerable political intelligence at the service of the organisation. He ensured that the pro-life campaigns would be adequately documented by securing access to its proceedings for a Ph.D. student, Tom Hesketh, whose subsequent book, The second partitioning of Ireland? the abortion referendum of 1983 (1990), was widely drawn on by later writers. Although O'Leary retained a lifelong attachment to the pro-life cause, he differed from most of his allies in his support for the 1992 amendment to the Irish constitution proposed by Albert Reynolds's government to restrict the scope of the judgment in the X Case. While most pro-lifers saw this as unacceptably lax and joined their opponents in calling for its defeat, O'Leary believed it was the best attainable outcome under the circumstances. (He had earlier opposed those within the pro-life movement, who wanted to reject the 1983 amendment, by using the same argument: that this was the best obtainable concession in the political circumstances.)
O'Leary also thought the pro-life cause was damaged by alliance with hard-core opponents of Irish membership of the European Community (latterly the European Union). He was a longstanding Europhile, who informed Garret FitzGerald (qv) that his support for French as the diplomatic language of the European Community reversed the replacement by Gearóid Mór FitzGerald (qv) of French with English as the language of Irish administration in the late fifteenth century. His religious views also influenced his interest in international development charities and issues.
In 1977 O'Leary published Irish elections, the first account of the electoral history of the post-independence state. In 1986 he collaborated with Rick Wilford and Sidney Elliott on the standard account of The Northern Ireland assembly, 1982–1986. He was a regular contributor to journals such as Irish Political Studies, and an active member of the Irish Committee of Historical Sciences. (His papers in connection with ICHS are held by UCC.) For his published work he received a D.Litt. from the National University of Ireland and was elected to membership of the Royal Irish Academy.
His last book (with Patrick Maume), Controversial issues in Anglo-Irish relations, 1910–21, was published by Four Courts Press in 2004; Maume did the archival research, discussed the subject with O'Leary, and carried out editorial work, but the basic text was O'Leary's (composed in his beautiful longhand; he never learned to type). A proposed sequel dealing with Anglo-Irish relations in the period after the 1921 treaty never materialised. One topic intended for this sequel was the 1940 Malcolm MacDonald mission to Ireland in which de Valera was offered Irish reunification in exchange for entry into the second world war on the allied side.
O'Leary was always somewhat shy and maladroit in personal dealings with women; in later life he expressed regret over his failure to marry and felt he had neglected possible marriage opportunities by allowing himself to become married to his work. His transient lifestyle contributed to the alcoholic episodes which marked his later life; he attributed their inception to the academic habit of socialising in bars. During periods of heavy drinking (accompanied by terrifying depressive spells) he looked for help to some of his older academic friends, and though he could prove a considerable trial he generally received patience and kindness; on more than one occasion he undertook a residential drying-out spell. His last years were marked by ill health; a spinal complaint caused partial paralysis before it was detected. He died in hospital in Belfast on 7 September 2006 after suffering a stroke at his flat in the Belgravia Buildings, Lisburn Road, earlier in the day; he is buried in the O'Leary family plot in Timoleague Abbey, west Cork.
In appearance and habits O'Leary was the old-style bachelor don, and like many such his abilities were better seen in conversation and in journalism than in less ephemeral works. Despite his idiosyncrasies he inspired affection even among many who thought some of his causes misguided.