Ronan, Sean Gerard (1924–2000), civil servant and diplomat, was born 11 January 1924 in Cork city, the eldest of the three children, two boys and a girl, of John Ronan of Ballintemple, Cork, and his wife, Mary, née Hogan, of Portumna, Co. Galway. He was educated locally and then at the Capuchin College, Rochestown, Co. Cork (1937–41), and at the Presentation Brothers' school in Cork (1941–2). He was first appointed to the civil service in 1942 as an executive officer with the revenue commissioners, and served in this capacity until 1946, the year that he graduated from UCD with a BA (first-class honours) in legal and political science. He was appointed administrative officer at the Department of Finance and completed an MA (first-class honours) at UCD in 1947. He completed an LLB in the following year, also at UCD, and again with first-class honours.
In 1949 Ronan transferred to the Department of External Affairs, serving as third secretary, and in the following year served at the consulate-general in New York. In 1951–5 he was first secretary, servicing Ireland's membership of the Council of Europe at Strasbourg, before being appointed consul-general in Chicago in 1955, where he formed a close relationship with Mayor Richard Daley. He was a member of the Irish delegation on the second committee (economic) of the United Nations general assembly in 1958–9, and in 1960 he became head of the political and information divisions at the Department of External Affairs in Dublin. He then served as a delegate on the first committee (political) at the UN in 1961, and in 1964 he was appointed departmental assistant secretary in charge of political, information, culture and international organisations affairs, including the United Nations, also working in the same period as chairman of the interdepartmental committee on publicity abroad. In 1965 he was one of three senior diplomats who went to Pentonville prison to receive the remains of Roger Casement (qv), which were being returned by the British government, and in the same year he was a member of the Irish delegation on the first committee (political) at the UN general assembly, serving in the same capacity in 1967–71. As assistant secretary at the Department of External Affairs, he was centrally involved with the unfolding Northern Ireland crisis in 1969 and became chairman of a special section to coordinate northern policy, the genesis of the later Anglo-Irish division within the department. In 1972 he was appointed Irish ambassador to West Germany, before being seconded as Ireland's top-ranking eurocrat to the post of director-general of information at the European Commission in 1973–7. He then served as ambassador to Greece and non-resident ambassador to Israel in 1977–84. He was made ambassador to Japan with accreditation to Seoul, South Korea, in 1984, remaining in this position until he retired in 1988.
Ronan was Ireland's most senior official at the European Commission during the first years of Irish membership of the EEC, and his role in protecting Irish interests at the UN on economic and political committees was also considerable. His contribution to the formulation of northern Ireland policy in 1969–72 proved substantial; in a memo of 1969 he closely anticipated the approach adopted by various governments in later years when he wrote that ‘the use of force, emotionalism and opportunism must be proscribed. Our approach must be sincere, realistic, logical, pragmatic and unrelenting at all times’ (Irish Times, 4 Mar. 2000).
Having developed a passionate interest in Asian culture, he was appointed Irish governor on the board of the Asia–Europe Cultural Foundation in 1997. His long-standing interest in Japanese culture and the nineteenth-century Anglo-Irish-Greek writer Lafcadio Hearn (qv), known as the first westerner to become Japanese, led to his publishing Lafcadio Hearn (Koizumi Yakumo): his life, work and Irish background (1991) and Irish writing on Lafcadio Hearn and Japan: writer, journalist and teacher (1997). He also compiled a Catalogue of the Lafcadio Hearn Library at the embassy of Ireland, Tokyo (1988). He enjoyed many honours, including the Irish Local Defence Force service medal (1945), the great order of merit with star (Grosse Verdientskreuz mit Stern) of the Federal Republic of Germany and the diplomatic service order of merit of the Republic of Korea (1988).
On 15 November 1949 he married Brigid Theresa of Castlebar, Co. Mayo, daughter of Richard James McGuinness, company secretary, of Castlebar, Co. Mayo, and his wife, Margaret, née McElroy, of Lisnaskea, Co. Fermanagh. They had four children, three daughters and a son, Niall, who died in Australia in 1977. Sean Ronan died 27 February 2000 at St Vincent's Hospital, Elm Park, Dublin.