« Reply #5 on: Wednesday 04 April 12 20:32 BST (UK) »
using the IGI for research in most of Wales before 1813 is a bit of a problem. Some of the counties have few marriages and the baptisms are transcribed as if they were patronymic even when they weren't. So, for instance, John, the son of William Edwards, would be indexed as John Williams & show his father as William Edwards. Unless you know in which parish the person was baptised, you'll struggle to dinf them as you need to search an IGI batch by first name and approx year.
Also, you have the possibility that the family was non-conformist and so there is no parish baptism to be found. The existence of a parish marriage is no clue to their denomination as all marriages had to take place in the parish church to be legal after Hardwicke's Marriage Act, the only exceptions being Quakers & Jews. And not all denominations practise infant baptism.
FreeReg has some coverage of parish records for Carmarthenshire & doesn't use the patronymic form. I'm sorry I can't remember if you have a parish of birth for William. Do you have a reason for thinking he was born in Talley? The marriage was in Llangadock, wasn't it? Do you have a copy of the parish entry to see if the names of witnesses are family members?
Cornwall: Allen, Bevan, Bosisto, Carnpezzack, Donithorn, Huddy, James, Retallack, Russell, Vincent, Yeoman
Cards: Thomas (Llanbadarn Fawr)
Glam: Bowler, Cram, Galloway, James, Thomas, Watkins
Lincs: Coupland, Cram
Mon: Cram, Gwyn, John, Philpot, Smart, Watkins
Pembs: Edwards (St. Dogmael's)
Yorks: Airey, Bowler, Elliott, Hare, Hewitt, Kellett, Kemp, Stephenson, Tebb