Guinness, Henry Seymour (1858–1945), governor of the Bank of Ireland and assistant managing director of Arthur Guinness, Son & Co. Ltd, was born 24 November 1858 in Dublin, eldest son among five sons and seven daughters of Henry Guinness (1829–93) of Burton Hall, Stillorgan, Co. Dublin, and his wife Emelina, daughter of James Brown of Edinburgh, Scotland. He was educated at Winchester and the Royal Indian Engineering College, where he was Argyll scholar for 1879. After graduating he worked (1880–95) with the Indian public works department. While in India he joined (1884) the Burma State Railway Volunteer Rifles; during his time with them he was awarded the Burma medal and three clasps. In 1894 he became an associate member of the Institute of Civil Engineers. He left India in 1895 to return to Dublin, and was high sheriff of Co. Dublin in 1899. In 1902 he was appointed a director (1902–24) of the Great Northern Railway and in 1910 he became a director (1910–24) of the Bank of Ireland.
Although not a politician by profession, and despite his natural unionist leanings, he accepted the inevitability of Irish independence. He believed the Irish Free State needed the support of the business community to avoid chaos and anarchy. His views of the new state and his prominent role within the unionist-dominated business establishment led to his appointment (1922–34) to the Irish Free State senate in 1922. Having held the position of deputy governor of the Bank of Ireland from 1920, he became governor in 1922. As finance minister of the provisional government, Michael Collins (qv) asked the bank to act as bankers to the new regime. Guinness was of the opinion that the bank should support the new government because it was attempting to maintain law and order, which was essential to the bank's interests. The bank had already experienced several raids throughout the country, and on 1–2 May 1922 no fewer than twenty-six branches were raided by Irregulars. He also witnessed the effects of the civil war personally when he was turned out of his home by anti-treaty forces and the house was set alight. In June 1923 the Irish government notified the bank that it wished to raise a loan of £7 million from the Irish banks. As chairman of the Irish Banks Standing Committee he was requested by the other banks to seek a British guarantee for the loan. Realising that this would merely undermine the Irish government, and thus be counterproductive to the banks, he broke the deadlock by agreeing to support the loan if the other banks did. The other banks had little choice but to follow suit and a loan of £3 million was granted. The following November he also gave his tacit support to a £10 million national loan. The unionist-dominated banking community thus cemented firm ties with the new state, which eased the transition for both parties. In addition to this the dividends of the bank for his period as governor were higher than they had been since 1873.
In 1924 he joined the family brewing business of Arthur Guinness, Son & Co. Ltd. as assistant managing director (1924–30). During his tenure profits returned to the levels of before the first world war, and dividends were as high as 32 per cent (1925, 1926). However, these profits were the result of a fall in the cost of raw materials and therefore masked a consistent decline in sales throughout Ireland and Britain. The reaction of the company to this decline marked a watershed: the importance of the Irish market began to wane in relation to Britain and, more significantly, the company launched its first advertising campaign. The trial campaign, with a budget of £15,000 and launched in Scotland, stressed the alleged medical benefits of Guinness and used the subsequently famous slogan ‘Guinness is good for you’. The success of the Scottish advertisements led to a rise in sales in 1929 and resulted in a similar campaign in England with a budget of £250,000.
Shortly after returning to Dublin he was appointed (1899) to the council of Alexandra College, Dublin, of which he was subsequently (1913–40) vice-warden. He was elected MRIA in 1911. In addition to his careers in engineering, banking and business he took a deep interest in the genealogy of the Guinness family and his findings were published posthumously as The Guinness family (1953). He died 4 April 1945.
He married (1900) Mary Middleton Bainbridge, daughter of Robert Stagg Bainbridge of Keverstone, Co. Durham, England. They had four daughters and lived at Burton Hall, Stillorgan, Co. Dublin, until shortly before his death, when they moved to Broadwater House, Tunbridge Wells, England.