Well, I searched on Family Search and found a link to her baptismal record, but the image itself is on Find My Past. I do not have a subscription to them. They do offer a free trial, but I don't want one because it would be useless to me. Here is the link to the link on Family Search: "England, Middlesex, Westminster, Parish Registers, 1538-1912," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:KCCJ-2L6 : accessed 16 April 2016), Gwyneth Dora Howells, 1914, Baptism; from "Parish registers 1539-1945," database and images, findmypast (http://www.findmypast.com : n.d.); citing St Martin In The Fields, Middlesex, England, City of Westminster Archives Centre, London; FHL microfilm 561,149.
If that's confusing (it's confusing to me!), simply type her name in the search box on Family Search and the year 1914 and England as the place of birth. It was the first record that showed up on the page.
The records are there, they're just not free. Her baptismal record should have both her parents names.