Guinness and her husband divided their time between London and Clandeboye, living at 4 Hans Crescent, Knightsbridge in London. Guinness preferred London, but would throw large parties at Clandeboye, where she was known for her practical jokes. Her husband was killed in 1945 in Burma during
World War II, leaving Guinness widowed with three young children. He left the estate heavily mortgaged due to gambling debts, but Guinness had the money to redeem it, buying the estate for £192,000. She then created the Clandeboye estate company, similar to the
Iveagh Trust. On 14 September 1948, she married Major Desmond Buchanan, a former army officer and antiques dealer. They divorced in 1954, after which she married Judge
John Maude on 20 August 1955. They lived largely apart for a number of years, and Guinness continued to use her title from her first marriage. Guinness was known for her unusual sense of fashion, and is believed to have provided inspiration for
Barry Humphries’ character
Dame Edna Everage and
Osbert Lancaster's
Maudie Littlehampton in
The Daily Express. After the death of her father in 1949, she and a cousin became the first women to sit on the board of the
Guinness Brewery. She later became active in charitable work, raising £50,000 between 1958 and 1965 to build the Horder centre for arthritics as well as donating the site in Sussex. She stood down from this committee due to a disagreement, but she later opened Maureen's Oast House in 1996, as a holiday home for arthritics on her Kent estate. Upon his marriage, she presented Clandeboye to her only son, Sheridan, in 1966. She gave all her children generous annuities, but was noted as less maternal than her sister Oonagh. Her daughter Caroline once commented that her childhood was too painful to recount, and her eldest daughter Perdita stated that all her mother wished to talk about was her glory days in London society. Her daughters and daughter-in-law unsuccessfully contested in court Guinness's passing of assets worth £15 million directly to her two grandchildren in 1995. She died on 3 May 1998 in London. She is buried at Clandeboye with her son, who predeceased her. ==In popular culture==