Following the information from ckirkph, I have searched for the birth registration etc of Doris Calvert. This appears to be in Conwy Registration District in the December quarter of 1931. Birth of Doris Calvert, mother's maiden name Jones.
There are a few Family Trees for her on Ancestry as well. It appears that John Calvert and Mary Jane Jones had three children:
Gladys Jane Calvert, 1927-2017
Beryl Hilda Jones, 1929-2009
Doris Calvert, 1931-2009.
Gladys and Doris were born in Llandudno, Beryl was born in Conwy.
John Calvert and Mary Jane Jones married in the Welsh Congregational church in Llandudno in 1920.
I note that Mary Jane Calvert, nee Jones died in 1941. Her place of death is shown as 21 Brook St, Llandudno.
There is some variation in the Family Trees on Ancestry. One has Beryl Hilda Jones as Calvert. This tree shows John Calvert and Mary Jane having had 7 children.
I checked to see what name was used in the registration of Beryl's birth in 1929. This is confirmed as being registered Calvert.
Helig.