Mary Jaqueline Tyrwhitt was born in Pretoria, South Africa on May 1905. She attended St Paul's Girls School, Hammersmith, as a Janyon Scholar, matriculating in 1922. She had hoped to work for a history scholarship to Oxford. Instead, in 1923, she entered the Royal Horticultular School studying for the General Horticultural Diploma, which she got in 1924.From 1925-26 she was a student-gardener at Warley Place under the famous Edwardian gardener Miss Ellen Willmott.Her fist job, lasting two and a half years, was with a firm of garden architects in Vernon Square in London. She assisted in laying out some three hundred gardens for them. She was a sole surveyor, draughtsman and designer in the firm and soon realised she was being over-worked and under-paid. She was a night student as the London School of Economics as well.In 1929 she run the office of the Imperial Society of Knights Bachelor in Lincolns Inn. In 1931 she became Assistant Organiser for the Leaque of Industry. In 1935 she left the Leaque of Industry in order to study "the association of argiculture with industry" at Dartington Hall. In 1937 she spent nine months in Berlin, taking a course in town planning at the Techniche Hochschule. On her return to England she accepted a three-year Rowntree grant to study problems of town and country planning for the Town and Country Planning Association, preparing a social survey of Welwyn Garden City. At the same time she took a night course at the School of Planning and Regional Reconstruction under E.A.A. Rowse, obtaining an honours diploma.In 1941 E.A.A Rowse was called up and she replaced him as Director of research at the School of Planning and Regional Recostruction as well as Director of Studies at the School of Planning and Research for Regional Development.In 1945 she was invited by the Royal Architectural Institute of Canada and the American Office of War Information to lecture on British town planning in war conditions. From 1955-56 she was at Harvard Univercity, first at Assistant Professor of City Planning and from 1958 as Associate Professor of Urban Design. She was UN advisor in Indonesia to establish a new programme in city and regional planning in 1960, and, in 1961-62 a Ford Foundation grant enable her to engage in a research project, "The city of the future", at the Athens Centre of Ekistics.She was a brilliant editor. Apart from the works of "Geddes" and "Giedion", which she edited, translated and reissued, she edited and translated Doxiadis' great work "Architectural space in ancient Greece" which was published in English in 1972. Although she had retired from her professorship at Harvard in 1969 and had the absorbing interest of her garden at Sparoza, she taught at the Graduate School of the Ekistics until 1972 and had a full-time appointment as editor of "Ekistics" from 1969-72, after which she was consultant editor until her death.