Guinness

The Gaelic Mag Aonghusa or Magennis kindred ruled the territory of Iveagh in modern County Down from the 12th century into the 17th, the senior chiefs styled Lords of Iveagh through the early 17th century. Family tradition traces the modern Guinness line to a cadet branch of that house; the peerage choice of 'Iveagh' in 1891 explicitly affirmed the connection.

Arthur Guinness (1725-1803) leased the four-acre St James's Gate brewery in Dublin in 1759 on a 9,000-year lease for £45 a year, and within a generation built the family business into the largest brewery in Ireland. By the early 19th century Guinness porter had displaced the imported English ales across most of the Irish market; by the 1880s St James's Gate was the largest single brewery in the world.

Edward Cecil Guinness (1847-1927), Arthur's great-grandson, took the brewery public on the London Stock Exchange in 1886 in what was then the largest IPO in history, and was created 1st Earl of Iveagh in 1891. At his death in 1927 he was the wealthiest man in Britain. His philanthropy paid for the restoration of St Patrick's Cathedral in Dublin, the Iveagh Trust housing schemes in Dublin and London, the Lister Institute of Preventive Medicine, and the gift of Kenwood House in Hampstead to the nation.

The Guinness political branch ran through Walter Guinness, 1st Baron Moyne, who served as Colonial Secretary in the wartime cabinet of Winston Churchill, and through his Moyne descendants. The senior brewing line carries the current 4th Earl of Iveagh, who returned the family seat at Elveden Hall in Suffolk to active estate management. Guinness Brewery merged with United Distillers in 1997 to form Diageo, the world's largest spirits company; the Guinness family retains a substantial holding.