I can see David and Edith together in Cynon Terrace, Llwydcoed up to 1967 on electoral registers.
David dies in 1978, with an address in Norton, Mumbles. I've been having difficulty with a death for Edith
This one caught my eye as the dob matches 1939
Edith Owen Allanson
Birth Date 4 Apr 1905
Registration Date Feb 1991
Swansea Vol 27 p2131
Marriages Q4 1981
YORK Vol 2 p1967
ALLANSON GEORGE H DREW
DREW EDITH O ALLANSON YORK 2 1967
Probate register confirms its our Edith - her address is the same as for David Charles Drew's death