Granddaughter of the first Earl of Iveagh and daughter of Ernest Guinness, Maureen was already appearing in those columns in January 1924, when it was noted that she and her two sisters, Oonagh and Aileen, "vivacious young daughters of Ernest Guinness", had left "Socialist Britain" to join their father's yacht Fantome II on its leisurely world cruise. As one of the Bright Young Things, all blonde bob and blue eyes, she provided a focus for a media age which fed on such celebrities.
As Andrew Barrow's 1978 book Gossip proves, Maureen Guinness's every move was noted: when she stayed at Longleat for Henry Bath's coming of age party in July 1926, it was worthy of remark that her current nickname was "Teapot". Her peer group included Evelyn Waugh, Harold Acton, Bryan Guinness and his fiancee, Diana Mitford; her best friend was Teresa ("Baby") Jungman, and Maureen swelled the ranks of that "adoring group of Guinness girls" whom Cecil Beaton so envied.
On 3 July 1930, she mamed her cousin Basil Hamilton- Temple-Blackwood, styled Earl of Ava, son and heir to the Marquess of Dufferin and Ava, at St Margaret's Westminster. "The best brain of my generation", according to James Lees-Milne, he became Parliamentary Under- Secretary to the Colonies and a Government Whip in the Lords; when Maureen gave birth to their son, Sheridan, in 1938, it was noted that she was wife to one of the youngest members of the Government.
The family lived at Clandeboye, a 3,000-acre estate in County Down, but Maureen continued to play her role in London society, her forthright manner not always admired. She told Hugo Vickers how, in 1935, Beaton introduced her at a dinner party: "Do you realise that you have here, in Maureen Dufferin, the biggest bitch in London!" Their friendship was severed for some years.
Clandeboye became dilapidated during the Second World War and required substantial injections of cash to keep it up. When the marquess was killed in action in Burma in 1945, Maureen discovered the house had been heavily mortgaged to meet gambling debts. Three years later she married Major Desmond Buchanan, retaining her title "out of deference to the wishes of her first husband". She was given away by her 10-year-old son, Sheridan. The marriage lasted just six years; in 1955 she married as her third husband Judge John Maude (he died in 1986).
In 1949 she became a director of the family business, the Guinness brewery. "It's hard to say what my duties will be," she told the press, who believed the marchioness to be a teetotaller, "but I think I shall go into the office every day." Beyond her society profile and her homes in London, Kent and Sardinia, Maureen Dufferin found time for charitable works, from the faintly ridiculous - in 1954 she played a ladies' lavatory attendant in Princess Margaret's charity amateur production of The Frog at the Scala Theatre - to the more substantial founding of a holiday home for arthritics in Lamberhurst, Kent.
Throughout the Fifties and Sixties she played her role as part of the international set who moved restlessly around the world. In 1961 she visited Noel Coward and the Flemings in Jamaica, and in 1965 was "the rehearsal" for Coward's famous lunch party for the Queen Mother. In the meantime, her progeny distinguished themselves, not least in their marriages. The outspoken and talented author Caroline Blackwood (who said she found her childhood too painful to speak about) married, in succession, Lucian Freud, Israel Citkovitz and Robert Lowell, while in 1964 the flamboyant and basically homosexual Sheridan married Lindy Guinness, daughter of Loel Guinness.
Family feuding broke out in the long-running legal battle of the 1990s, when Maureen Dufferin's daughters and daughter-in-law brought a lawsuit challenging her right to transfer the benefits of a trust fund to her granddaughters Evgenia and Ivana. The dispute was settled in Maureen's favour in 1995 (her somewhat inexplicable concerns over money having already surfaced in 1980 in an acrimonious legal dispute with a butler accused of stealing crab apples and tea towels).
Despite such shortcomings, Maureen Dufferin was remarkably attractive, animated, personable, and possessed of a forthright manner. She appeared to relish her part in the BBC2 "expose" film by Philippa Walker, Guinnesty, in which she was interviewed at length and spoke with candour about her relations. Even in her nineties she was still throwing lively annual dinner parties for the Queen Mother at her home in Knightsbridge, at which the likes of Sir Alec Guinness and Barry Humphries could be found. Indeed, in later life the marchioness - the model for Osbert Lanchester's Maudie Littlehampton - appeared also to have inspired Dame Edna.
She was truly a survivor from another era. When I met her at a book launch in 1996, she was wearing an exaggerated black oilskin sou'wester (it had been raining heavily), a 1940s-style fur coat with padded shoulders, platform shoes and pale blue and multicoloured rhinestone spectacles. When I was introduced as Noel Coward's biographer, she remarked, "What a pity they didn't have sperm banks in those days" - the word "sperm" rang out loud and clear through the reverent hush of Hatchards: "we could do with more Noel Cowards." Some might think we could do with more Maureen Dufferins, too.
Maureen Constance Guinness: born 31 January 1907; married 1930 Basil, Earl of Ava (succeeded 1930 as fourth Marquess of Dufferin and Ava, died 1945; one daughter, and one son and one daughter deceased), 1948 Major Desmond Buchanan (marriage dissolved 1954), 1955 Judge John Maude (died 1986); died London 3 May 1998.