Margaret Tomlinson was born Margaret Tansley in London on 20 September 1905. Her father, Sir Arthur Tansley, was Professor of Botany at the University of Oxford. She studied architecture at Newnham College, University of Cambridge, from where she graduated in 1927 and later obtained an MA.
A photograph and plan of a cottage in Devonshire, England, designed by her is illustrated in 'Decorative Art' 1932 (p.112). Most of her professional career, however, was taken up as an investigator and photographer first for the National Buildings Record and then for Victoria County History (VCH). During her first ten years with the VCH she was employed as part-time staff architect. She was then appointed to a full-time post. Tomlinson played an important part in reviving the VCH project following World War Two and wrote articles and took photographs for several of the county histories. She died in Uttlesford, Essex on 9 October 1997.