Hi David,
Thanks for the information it is wonderful. Since I posted the original message I had joined Ancestry and also found the same info you did, and you were on exactly the right track.
Elizabeth Dyer married David Davies although I have not found a marriage for them yet, it must have been about 1846 as their first son Thomas was born about 1847.
The marriage record you found didn't happen to list parents of Anne or Thomas or their ages by chance did it? I know Thomas had a brother or cousin called William Dyer who married Mary Thomas. William was also a shoe maker like Thomas.
I have found three christening records in the right area for the children of a John Dyer of Llangathen. The three children listed are Thomas (5 Jun 1786), William (9 Apr 1792) and Mary (13 Apr 1789) but I have not been able to confirm if the Thomas and William christened are the same Thomas and William I have in my tree.
I know there is definitely a family relationship between Thomas and William though, as William's daughter Cecelia was living with Isaac (and co.) in one of the later census. Interestingly Cecelia also married a man with the surname of Thomas (like her mothers) so he may well have been a cousin too.
Anyway the search continues. Thanks for your help.
Regards
Debby