Hi
Doris Jones at 10 Maxwell Road in the 1939 Register has two surname alterations, first to Stevens, then to Field (that second marriage was in Bournemouth in 1967)
So Doris Jones and Sister Stevens appear to be the same person!
In the Midwives Roll, 1958/9 (on ancestry), she is under the Jones name.
Doris Jones, Gestingthorpe Nursing Home, 10, Maxwell Road, Bournemouth, Hants.
Her date of enrolment was 26-11-32.