Dame Kathleen Mary Ollerenshaw, née Timpson, DBE (1 October 1912 – 10 August 2014) was a British mathematician and politician who was Lord Mayor of Manchester from 1975 to 1976 and an advisor on educational matters to Margaret Thatcher's government in the 1980s.

She was born in Withington, Manchester. Deaf since the age of eight, she loved doing arithmetic problems as a child. As a young woman, she attended St Leonards School and Sixth Form College in St Andrews, Scotland where today the house of young male boarders is named after her. At the age of 19 she gained admittance to Somerville College, Oxford, to study mathematics. She completed her doctorate at Somerville in 1945 on "Critical Lattices" under the supervision of Theo Chaundy. She wrote five original research papers which were sufficient for her to earn her DPhil degree without the need of a formal written thesis.

While an undergraduate, she became engaged to Colonel Robert Ollerenshaw, who became a distinguished military surgeon, a pioneer of medical illustration, and was High Sheriff of Greater Manchester from 1978 to 1979. They married in September 1939. After the Second World War, the Ollerenhaws moved to Manchester, where Kathleen worked as a part-time lecturer in the mathematics department at Manchester University and continued her work on lattices. In 1949, at the age of 37, she received her first effective hearing aid.

Ollerenshaw served as a Conservative Councillor for Rusholme for twenty-six years (1956–1981), was Lord Mayor of Manchester (1975–1976), and the prime motivator in the creation of the Royal Northern College of Music. She was made a Freeman of the City of Manchester and was an advisor on educational matters to Margaret Thatcher's government in the 1980s.

She was President of the Institute of Mathematics and its Applications from 1978 to 1979. She published at least 26 mathematical papers, her best-known contribution being to most-perfect pandiagonal magic squares. An annual public lecture at the School of Mathematics, University of Manchester, is named in her honour.

An amateur astronomer, Ollerenshaw donated her telescope to Lancaster University, and an observatory there bears her name. She was an honorary member of the Manchester Astronomical Society and held the post of Vice President for a number of years.

Ollerenshaw attended St Leonards School in St Andrews, Fife, and served as the school's president from 1981 to 2003. She was succeeded by Baroness Byford, Conservative spokeswoman in the House of Lords. She turned 100 in October 2012.

She died in Didsbury on 10 August 2014.

Miscellanea

• Composer Sir Peter Maxwell Davies dedicated his Naxos Quartet No.9 to her.

• Ollerenshaw had an Erdős number of 5 by way of Hermann Bondi, Ivor Robinson, Peter Bergmann and Ernst G. Straus.

Honours

In 1970, Ollerenshaw was appointed Dame Commander of the Order of the British Empire for services to education.