Painter, sculptor, etcher, weaver and jeweller. He studied for three years at the Anglo French Art Centre and was assistant to Barbara Hepworth from 1959 to 1962. He was also assistant to Denis Mitchell in St. Ives.

Son of the playwright Sean O'Casey, for most of his career Breon O'Casey has lived in Cornwall and has been closely associated with the St. Ives School of painters and sculptors. He benefited from his friendship with some of the leading artists of his generation such as Peter Lanyon, John Wells and Tony O'Malley.

His first one-man show of paintings was at Somerville College, Oxford, in 1954. He has regularly exhibited with the Penwith Society. His paintings have some characteristics of the St. Ives School, being small abstracts, often on irregularly shaped pieces of wood, executed in warm earth colours;

simple, 'primitive' and eloquent in outline.

Although his gold and silver jewellery won him an international reputation with connoisseurs and his hand woven creations have been targeted by knowledgeable collectors, he now concentrates on painting, sculpture and graphic work.