She edited and published medieval texts including contributions to A Guide for Anchoresses and Sir Gawain and the Green Knight.
Day was born in the listed building of St Leonard's House in Linney,[1] Ludlow, Shropshire, in 1875.
Her father had been a fellow of St John's College, Cambridge before he became the headteacher of Sedbergh grammar school.
[2] Day was educated at Brighton High School for Girls, Girton College, Cambridge and the University of London, and thereafter worked as a teacher and lecturer.
In 1935 the EETS decided to publish editions of the Ancrene Wisse, an early 13th-century text also known as A Guide for Anchoresses.