My friend Michael Brennan, who has died aged 80, was a teacher and activist, and also tried to unravel the mathematical basis of Celtic interlace – the ornamental knot patterns found in Irish art.
As a youth Mike had assisted his father in his work as a monumental sculptor. He was fascinated by the mathematical forms embedded in Celtic interlace, and in 2004 embarked on a serious study of this field, finally completing a PhD at Bangor University in 2011, on the Structure of Interlace in Insular Art. Among his published work is the chapter The Lindisfarne Gospels: The Art of Symmetry and the Symmetry of Art in Richard Gameson’s 2017 volume The Lindisfarne Gospels: New Perspectives. He later became drawn to Byzantine and early Islamic art.
Born in Kilkenny, Ireland, to Ellie (nee O’Gorman) and Dan Brennan, Mike went to school at St Kieran’s college in his home town, and studied for a BA degree in mathematics and statistics, then a higher diploma in education, at University College Cork. He later completed a master’s at Maynooth University. His first job was as a secondary teacher, but in 1968 a search for new pastures took him to a computer programming job in Manchester.
In this life-changing seven-year period, he encountered a network of like-minded activists devoted to nonviolent social change and an alternative society. Mike became a charismatic figure in campaigns around homelessness, inner-city housing, a libertarian school, free public transport and a radical Christian magazine. He kept the mathematics going through teaching at Salford College of Technology.
Returning to Ireland in 1975 he worked as a secondary teacher, and then, from 1985 until 2009, as a lecturer in mathematics and computing at Waterford Institute of Technology. He married Breda Heavey in 1984, and this opened a new life-chapter centred on family and community. But he always felt the fire of moral responsibility, be it at work, or through the teachers union or the local residents group. He spoke up and fought for what he believed in.
Mike had exceptionally wide interests. He loved to play music and write stories, and turned his hand to sewing, pottery, magic tricks, woodwork, painting and growing plants. His daughters appreciated his commitment to fun and craic, “supporting and stimulating our imagination … setting up games and riddles, dragging us off on adventures, and leading the celebrations of all the important moments of our lives”.
Mike was principled and passionate, gentle and caring, with a poetic streak that added to his charm. He was welcoming, witty, generous and loyal to his many friends, and a devoted, proud father.
He is survived by Breda and their daughters, Kate, Amy, Deirdre and Rachel, and grandsons, Max and Otis.