Daphne Gilbert obituary

My mother, Daphne Gilbert, who has died aged 80, was a respected mathematics professor. She defied the expectations foisted on most women of her generation, successfully combining an outstanding career in teaching and research with bringing up four children.

Having married at the age of 19 in the early 1960s, Daphne put her work ambitions on hold for many years until her children had become teenagers. Restarting her education, she went on to become a maths lecturer at Sheffield Hallam University, later moving to Ireland to be head of pure and applied mathematics at the Dublin Institute of Technology (DIT), where she was awarded a professorship shortly before her retirement.

In a field dominated by men – still only about 11% of mathematics professors in the UK are women – she was a trailblazer.

Daphne was born in Woking, Surrey, the second child of Nicholas Mansergh, a historian, and his wife, Diana (nee Keeton). At the Perse school for girls in Cambridge she fell in love with maths, developing a particular interest in geometry and noticing patterns in nature on her country walks. Despite being pushed towards domestic sciences by her parents, she insisted on studying A-levels in maths, further maths, physics and chemistry.

In 1961 she began a mathematics degree at New Hall (now Murray Edwards College), Cambridge, but within a year she married Paul Gilbert, a philosophy student. Although he was always supportive of her ambitions, she immediately gave up her studies to concentrate on looking after her family.

Paul subsequently took up a lectureship at Hull University, and after being a full-time parent for 15 years, in 1977 Daphne began a maths degree at Hull, quickly followed by a PhD and several research associateships in mathematics at the same institution. Together with David Pearson, her PhD supervisor at Hull, she developed the Gilbert-Pearson Theory of Subordinacy of Schrödinger Operators, research that became an established tool in spectral analysis and paved the way for many developments in the field of mathematical physics.

In 1990 she joined Sheffield Hallam University, where she developed new degrees and masters’ programmes, and then moved to DIT in 1999, rising to be a professor and, on her retirement in 2008, emeritus professor.

She continued her mathematical research and travelled widely to conferences at home and abroad.

Paul died in 2022. She is survived by their four children, Benjamin, Hester, Matthew and me, and nine grandchildren.