She was born on 6 September 1911, in Eddlethorpe, Yorkshire, daughter of the baronet of Sledmere. She trained in sculpture under Marnix d'Haveloose in Brussels from 1927 to 1932, then attended British School in Rome for six months. She established a studio on London and first exhibiting her sculpture in 1928. In 1934 she married Randal MacDonnell, Earl of Antrim. Their residence was Glenarm Castle, Co Antrim.
During the second world war she was active in the Women's Voluntary Service, organising canteens and hostels for the armed forces, and led a mobile hospital unit for former inmates of concentration camps, and after the war took part in a rehabilition mission in Holland and Germany with the Catholic Relief Services. Her sculpture included pieces inspired by this period, including "Belsen Mother and Child". She injured her hand in an accident in 1962, and, unable to carve, modelled figures for casting in bronze.
She caricatured her relatives and others and exhibited her cartoons. She contributed to magazines such as Country Life, Harper's, Queen, Revue Moderne, Sketch, Tatler and Vogue, and illustrated children's books in cartoon style. She wrote and illustrated The Antrim McDonnells (1977), a humourous history of the Earls of Antrim, and The Yorkshire Wold Rangers (1981), on the history and her own memories of a nomadic group from Yorkshire.
Se served on the Northern Ireland Arts Council, and was a governor of Belfast College of Art and a trustee of the Ulster Museum. She died on 27 August 1984 at Glenarm Castle.
- Carmel Doyle, "MacDonnell, Angela Christina (née Syles) ('Angela Antrim'), Dictionary of Irish Biography, (Eds.) James Mcguire, James Quinn, Cambridge University Press, 2009
- Alan Horne, The Dictionary of 20th Century Book Illustrators, Antique Collectors' Club, 1994, p. 73