Dempsey, Jeremiah Francis (1906–93), businessman, was born 14 October 1906 at 15 Victoria Villas, Clontarf, Dublin, the third child of Patrick Dempsey, postal clerk, and Ellen Dempsey (née Kenefick). He was educated at the CBS, Westland Row, and at UCD, where he graduated B.Comm. (1927). Captain of the football team at UCD, he also played soccer for Bohemians football club and was a member of the Irish Free State team that competed against Scotland in a junior international (c.1927). Dempsey was articled with Peterson, Morrison & Co. and qualified as a chartered accountant in 1931. He then worked for Kennedy, Crowley & Co. before being appointed the first secretary and accountant (1935–6) of Irish Tanners, Portlaw.
In 1937 Dempsey was recruited to the post of secretary and accountant of Aer Lingus and Aer Rianta. As the Irish aviation business contracted during World War II he also became secretary and accountant of Irish Shipping. Near the end of the war Dempsey was appointed general manager and secretary of Aer Lingus and Aer Rianta (the airports’ authority) (January 1943) and by 1947 he was also general manager of Aer Lingus, Aer Rianta, and Aer Linte. After the war he embarked on an expansion programme for the three companies, opening up routes to Europe as well as introducing additional destinations in Britain. In 1954 Aer Lingus became the first airline in the world to operate scheduled services to Lourdes and in 1958 it started its first service to the USA. Much of the success of Aer Lingus and Aer Rianta was due to Dempsey's drive and ability. It was he who developed the corporate culture and built Aer Lingus into a national institution with an international reputation. A great manager, leader, and communicator, he was shrewd and wily, especially in his relations with the government. A firm believer in management development, he is credited with being the first Irish chief executive to introduce a formal development programme for his executives.
Dempsey's zest for innovation and modernisation in management practice led to his becoming a founder member of the Irish Management Institute (IMI) on 9 December 1952.
He was a member of the first governing council and served as chairman between 1963 and 1965. During his tenure he oversaw the rapid expansion of the IMI and increased formal training courses by securing government funding for the first time. He also addressed the world conference of the International Council for Management in New York. President of the IMI in 1969–70, he was created a life fellow of the institute in 1970 and later chaired the ‘founding fund’ with Frank Lemass (qv), which raised £600,000 (1974) of the £1.2 million needed to develop a new site for the institute at Sandyford in Dublin.
Away from the aviation industry, Dempsey was a director (1955–73) of Bord Fáilte and for a period of nine months in 1955 was acting director general. In 1957 he became a member of the board of Aer Lingus, while retaining the post of general manager. He retired as general manager of Aer Lingus and Aer Rianta in March 1967, though he continued as a director of both companies until 31 July 1976. Following his retirement he was appointed a director of the Bank of Ireland, the National Bank, the Hibernian Bank, and the Hibernian Insurance Co. Ltd. He also became chairman of Bank of Ireland Finance (formerly Foster Finance), Heinz Éireann, IBM Ireland, Irish Ropes, Berger Paints Ireland, Weeks Natural Resources Ireland, National Cold Storage/Nordic Cold Storage, Eurofood (Singapore) Pte., and Daniel Morrissey & Sons. He was for a time a governor of St Patrick's Hospital, Dublin, and president of the Irish Computer Society.
Dempsey was a co-founder and president (1962) of the International Air Transport Association (IATA), president of the Irish Association for Economic and Social Relations, president of the Irish Marketing Institute, and co-founder (1978) of Co-Operation North (later Co-Operation Ireland). He was a life fellow of the International Academy of Management and a council member of the Institute of Chartered Accountants in Ireland. In 1963 he was made a freeman of Lourdes and in 1964 he was awarded the honorary degree of LLD by the NUI.
Dempsey married 5 July 1933 Mary Eveleen Keating, daughter of Patrick Keating. They had four sons and lived at Four Winds, Brighton Road, Carrickmines, Co. Dublin. He died 14 January 1993 in Dublin.