Is the Ancestry index simply in error? Or did they make an assumption that 18th century Welsh children were taking the father's given name as their surname? If the latter, how often would that be true? Thanks in Advance!
It would be true very often, it wouldn't be an assumption but a difference in the indexation ; welsh families were still using the patronymic method of naming children in some cases up to the 1850s. You'll find this more in the western reaches, West Caernarvonshire, Merionethshire, Cardiganshire, Pembrokeshire, West Carmarthenshire and some of the families were very early non-conformists...
Lets look at my great (2) grandmother the daughter of John Howell b 1790 and Mary Griffith, his wife b 1802 ; firstly her mother kept her maiden name despite marriage; in all the census's she and her siblings are called Howell, but on her marriage certificate she's known as Jones (John's). Her siblings seem to pick and choose what they are named depending on what they're doing - B.D & M they seem to like Jones and census seem to be Howell. Now to John and Mary's parent's ..John's father was Howel Edward and Mary's father was Griffith Jones. John's sibling was called Edward Howell and his children became eventually Howell despite playing with the surname Edwards on occasion.
This is just one family, if you follow other families in rural Wales this seems to happen a lot.
I am extremely lucky in that this family and others in my tree were Scottish Baptists (nothing to do with Scotland but a small breakaway group of Baptist set up in Wales in the 1790's. As they practised adult baptism the group recorded children's births but not just the child's name ....for example here is the text of my GG grandmother's entry:
1848 On this day was born, Elliw, daughter of John Howell, by his wife Mary Griffith, who was the daughter of Griffith Jones and Gwen Robert, present at the birth were Elliw Jones and Gwen Robert. Elliw Jones was the witness to John and Mary's marriage in 1824. There are pages and pages of such entries within the book; which covers the congregations of the Ramoth Chapel in Llanfrothen and Rehoboth Chapel in Harlech. My family have continued to bury their relatives in Rehoboth to the present day. I believe these records are available online but are not the easiest to find.
Nesta