Hi there,
I have been following this thread with interest and have a couple of suggestions to make and of course this is only my own opinion as to Ellen's possible parents.
Having searched all Dennis Mc Carthy's born c 1800 to 1825 living in the the Glamorganshire area whatever parameters I set I kept keep coming back to this family on the 1861 census just three years before Ellen's marriage date.
RG 09 4044/76 P 21 McCarthy family as follows : Llantwit Fardre area Glamorganshire
Dennis McCarthy born c 1812 age 49, labourer in chain works, born Ireland
with wife Catherine also born Ireland
Eldest son John born Swansea and daughter Ellen age 15 ( birth c 1846 which we know can vary ) also born Swansea along with five younger siblings born Pontypridd.
If this is your Ellen and going by the marriage witness there is an Ellen Riordan with family also on the 1861 census Llantwit Fardre area who may just fit the bill.
Now bear with me on this,thinking out side the box.
Perhaps Ellen's birthplace on the 1871 Neath census is a red herring.
If, as is often the case, someone else filled in the return on their behalf due to illiteracy they may just have asked her where she came from, not where she had been born and she replied Pontypridd. i e where she had moved to Neath from and not given her place of birth.
Another suggestion,It may be an idea to see if any of the younger siblings in this family also marry or were baptised in St Dubritius RC thus keeping a family connection to the church. This family minus Ellen is still in the same area in 1871.
Best Wishes and looking forward to hearing how this progresses.
Scatty
