Thanks everyone for the help, adding Winifred Ogle and Mary Christine Smith to my family! Looking around I think there is also another daughter Marguerite Smith born in Doncaster in 1931 (same name as Winifred's mother). Another Smith family tree, that also doesn't know who Winifred is, has 3 children, 2 boys and a girl, which doesn't quite match with my 2 girls and a boy, but its all marked private, so I can't see what is going on.
Anyway, the people on this website are the best, and I never fail to learn something when I ask a question. Thanks again for the fast work!