« Reply #10 on: Wednesday 16 May 18 20:24 BST (UK) »
well, you know his father was George, a labourer. If you have access to the parish registers for the area, you could build a picture of the local James families using the records and the census entries. If there's a family where you don't find baptisms, you could investigate them more thoroughly.
Some non-conformist records are available through the Dyfed FHS. It may be worth checking Pembroke as well as it's so near. The record office has records for the Wesleyan church in Pembroke but they start from 1839.
http://www.genuki.org.uk/big/wal/PEM/Monkton#ChurchRecordsAny marriages before the start of civil registration in July 1837 and after Hardwicke's Marriage Act were in the established church anyway, apart from for Jews & Quakers.
There may be wills, not seeing anything of use at the moment, though.
https://www.library.wales/discover/nlw-resources/wills/
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