John Johns, Clifton Cottage, Hewelsfield. (General)
I can't see any baptisms for Constance Margaret JONES or Jean Eunice JONES (as you say they were twins)
Assume Thomas W JONES married Annie MORRIS
There is a big gap between children
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?
Looking at GloucestershireBMD/FreeBMD
There is
Constance Margaret JONES (mother's maiden name: MORRIS, 1929 Gloucester (Barnwood District which doesn't cover Hewelsfield) -
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Jean Eunice JONES (mother's maiden name: HARRIS), September Qtr 1930, Forest of Dean, Chepstow, Lydney
Constance M JONES (mother's maiden name HARRIS - September Qtr 1930 - Chepstow
Connie on the 1939 census birth date given 27 June 1929