Kathleen Etheldred Pownall was born on the 15th January 1889, her birth registered at Kensington district, London, in the first quarter of that year. She appears on the 1891 census living at 5 Stafford Terrace, Kensington with her family. The household comprised: Henry Harrison Pownall (head, aged 37, working as a barrister), his wife Blanche Pownall and their two children: Kathleen E (aged two) and John C G Pownall (aged under one month).
Kathleen appears on the 1901 census of England and Wales as 12 year old Cathleen [sic] Pownall living at Ades, Cinder Hill, Chailey.
On the 1911 census 22-year-old Kathleen is recorded as a visitor at the home of Frances Mary Pownall (aged 56) at 44 Montague Road, Richmond Hill, Surrey. I'm guessing that Frances was either a sister of her father or perhaps a sister-in-law; it should be easy enough to verify. Both women are recorded as having "private means".
I am unsure when Kathleen's connection with Sussex 54 VAD began but she had certainly served with the British Red Cross Society since 1911. She is undoubtedly the same "K E Pownall" whose signature appears in Edith Oliver's album on the page dedicated to Sussex 54 VAD in 1913. British Red Cross Society files note that she subsequently served with Hampshire 46 VAD and worked in Adhurst St Mary Hospital.
Kathleen Pownall died in 1978 at the age of 89. Two of her three brothers: Lionel Henry Yorke Pownall and John Cecil Glossop Pownall would also serve their King and Country during the First World War.