Formidable and flamboyant dressmaker and socialite

Mai Geldof, who has died aged 105, was the last surviving sibling of four born to Zenon, a Belgian chef and restaurateur, and Amelia Geldof, the youngest of whom was Bob Geldof senior, father of the musician and businessman.

Born in 1909 and named Mary Eileen, she features in both the census of 1911 and 2011 as resident in the family home in Sandymount where she died. Fifi to family and close friends, she was otherwise known as Mai.

An early memory was of seeing the Custom House burning (1921) from the steps of her home. Educated at Dominican Convent Sion Hill in Blackrock, Co Dublin, she and her elder sister, Cléo, hit the Dublin social scene in the late 1920s.

The two sisters worked in their parents' Café Belge on Dame Street or Patisserie Belge below Finn's Hotel on Leinster Street and sold sweepstakes tickets, mainly to fund wild road trips and cruises in and around Europe with friends. London, Paris and Monte Carlo were favourite destinations. On one such trip, they chanced upon a Nuremberg rally and quickly apprehended the awful significance of it.

Mai Geldof knew many figures from the theatre from her work in the café and did some costume design for Mac Liammóir and Edwards at the Gate Theatre. Other admired customers included Maud Gonne and Constance Markiewicz. Trendsetters Mai and Cléo became fashion trendsetters in due course. Mai set up a dressmaking salon on Wicklow Street. Among her clientele were Lady Longford and the recently deceased Dr Maeve Hillery. Her dress-designing skills were highly regarded and her nieces benefited from them throughout their childhood.

She was an early member of the League of Health and Beauty (established in 1934) and even into her 90s challenged family members to touch their toes as she could.

She had a brutally forthright personality and would often recount, freshly ablaze with indignation, stories of unfortunate clients or workmen who had been on the receiving end of her outrage. In the 1960s, she staged a "sit-in" in the Dublin Gas Company till she got satisfaction on her complaint. Despite this, or perhaps because of it, she had a very wide circle of friends.

The toughness of her character is wonderfully captured by Paul Durcan in his poem Sandymount Strand Dog Songs from his The Art of Life collection.

She was aware of her social privilege. She was quietly involved in distributing vouchers for free milk to people living in tenements and poor housing. Throughout the 1950s and well into the 1960s, she ran a Christmas party in Barry’s Hotel in north inner city Dublin for approximately 100 poor children. She would gather unwanted toys and comics and inveigle her nieces and nephews into helping out. Angling As a young woman, she was introduced to angling through a boyfriend. She became passionate about fishing. She adored the west, particularly Lough Mask. Her nieces and nephews remember large salmon trout arriving in parcels by train into Heuston station, wrapped up in reeds and absolutely fresh.

Aged 69, she took up driving and got a licence under the 1979 test “amnesty”. She retired at 76 and took up woodwork, attending night courses. One of the first pieces she made was a drinks cabinet, which lit up on opening. Intrepid and indomitable, in her 80s she could often be found wall-papering or fixing tiles on her roof. She was also a passionate gardener.

Mai Geldof was only ever once in hospital, when she broke her hip in 2006; she refused to believe this fact to the end. She never married and is survived by her nieces and nephews and succeeding generations.