HI,
If you look at the BDM Indexes most of what you are saying can be found there.
When Dudley and Gwen married in 1931 his father was named as Henry and hers as Charles Edward. (This is information they provided themselves)
The birthdate you have for Gwen matches that exact of a Gwendolyn Olive DUNK with parents Charles Edward DUNK (1884-1969) and Netea Olive CHICK.
Charles born 10 Oct 1884 father Thomas and mother Caroline Louisa Augusta BROCKMANN.
Google SA BDM if you don't have an Ancestry subscription.
Kellie