Guinness, Mahon and Co , bankers

Guinness and Mahon, land agents, was established in Dublin in 1836 by Robert Rundell Guinness (1789-1857) and John Ross Mahon (1814-1887). Within a short time, banking became the firm's main concern. It was renamed Guinness, Mahon and Company in 1851 and a London agency was opened in 1873. In 1916 three of Robert Rundell Guinness's grandsons retired from the firm following the death of their father, Richard Seymour Guinness, and the London office was closed. Their cousin, Howard Rundell Guinness was left with the small banking firm in Dublin. The London office was reopened in 1923 by Howard Rundell Guinness and his three sons (Henry Samuel Howard Guinness, Edward Douglas Guinness and Arthur Rundell Guinness, who became partners in the firm).

The firm in Ireland was registered as a private unlimited company in 1942, with the name Guinness and Mahon. The London business was henceforth called Guinness, Mahon and Company. In 1963 Viking International Corporation Limited (previously known as Viking Tanker Company Limited) acquired all the share capital of Guinness, Mahon and Company. Viking International Corporation Limited was renamed Guinness Mahon Holdings Limited. In 1973 Guinness Mahon Holdings Limited and Guinness, Mahon and Company Limited were acquired by Lewis and Peat Limited. The new holding company was called Guinness Peat Group Limited. The merchant bank, Guinness, Mahon & Company, continued business under the same name. In 1988 Guinness Peat Group was demerged into three groups: Guinness Mahon Holdings comprising the Guinness Mahon merchant bank and related investment management; Fenchurch Insurance; and off-shore activities. In 1991 the Bank of Yokohama acquired full ownership of Guinness Mahon Holdings. In 1998 it was sold to Investec of South Africa.

The London firm was based at St Swithin's Lane ([1873]-1901), 81 Lombard Street (1902-1916), 20 Bishopsgate ([1923]-1926), 53 Cornhill (1927-1964), 3 Gracechurch Street (1964-[1976]), 32 St Mary at Hill ([1976]-).