Bailey was born as Mary Winifred Roberts in Weston under Penyard, Herefordshire, England on 17 December 1902 as the youngest child of waggoner William Roberts. Her mother died when she was young. She had at least two sisters, Edith and Esme.
By 1921, Bailey was living with her aunt and uncle in Amersham, Buckinghamshire. She married Victor John Bailey, her childhood sweetheart, in 1923. The couple had a son, Alan Gerald Bailey, in 1925.
Bailey was widowed in 1932. During World War II, she worked in Farnham Common, London, placing evacuee children with families. She was saddened by children with gas masks being separated from their parents.
After the war’s end, Bailey worked at a family-run pharmacy in Cippenham, London for around 25 years, before moving to St Albans, Hertfordshire to live with her son, a chief engineer for British Aerospace.
Bailey’s son Alan died in 2004 aged 79. She moved into a Maidenhead nursing home in 2009, where she lived until her death on 13 June 2013 at the age of 110 years, 178 days.