« Reply #36 on: Sunday 13 May 18 10:47 BST (UK) »
the other info is the family of John Jones, father of Jonathan. That John gives his place of birth as Carmarthenshire and in one census specifically Llanfynydd. I've given you the 1851 census when they've moved to Merthyr Tydfil after the death of Evan, father of John. And the 1841 showing the family with Evan before the birth of John and the baptism of John in Llanfynydd.
Same family in 1861 - John before his marriage to Ann Davies
7 Castle Street, Merthyr Tydfil RG9/4052 folio 77 pg 36
Mary Jones head widow 56
Thomas son 26 haulier
David son 23 collier
John son 17 haulier
all born Carmarthenshire
You'll need the marriage certificate for John Jones & Ann Davies to be sure of both fathers' names & occupations.
Possible marriage regs for John Jones & Ann Davies
dec qtr 1868 Merthyr Tydfil vol 11a pg 538
june qtr 1867 Merthyr Tydfil vol 11a pg 559
Just because the eldest son is named Thomas it doesn't mean John's father was called Thomas. You mentioned a Thomas Jones 1801-1875 and I can see no evidence from census entries of a likely candidate.
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