Mabel was born on 15/8/1900 in Llandudno, the daughter of grazier Harold F Rees (b. 1879) and Alice (b. 1875). She had a brother named Harold, born in 1903.
Mabel joined the Shropshire Reserves VAD, and from 9/7/1917 to the end of the war she worked full time as a storekeeper at Park Hall Military Hospital, earning 32s/6d per week.
Mabel married Thomas W Jones in 1931. The two ran a dairy farm together.