Thanks to bertieburrell and Roger, this is looking good, though nothing confirmed yet.
Put into a timeline:
1850 - DecQ: marriage of a John Thomas and Maria Evans in Merthyr Tydfil
1851 - census: John, 47, married, born Herefordshire, servant, brewer and ostler in the Sun Inn, Wheat St, Brecon
1856 - birth and baptism of daughter Mary Ann, father John a brewer and ostler, of Three Cocks Lane, Brecon.
1856 - death of a Maria Thomas in Merthyr in SeptQ 1856
1861 - census: John, unmarried, born Brecon, servant, brewer in the Sun Inn, Wheat St, Brecon; also a Mary A Thomas, aged 6, living with her grandmother in Brecon.
1876 - marriage of Mary Ann, father John listed as deceased coachman.
While the timeline looks good, there are a few puzzles...
- John is older than I expected, presumably Maria was younger than him
- different places of birth shown for John in 1851 and 1861, and unmarried in 1861 (but surely this is the same man)
- Mary Ann's birth and baptism give an address of Three Cocks Lane - in the middle of the 2 censuses when John is in the Sun Inn, Wheat Street.
There are a number of deaths for a John Thomas in Brecon between 1861 and 1876, so I'll look for him in 1871 to narrow it down (big help to have his age
), for Maria on her own in 1851, and wait to hear from Merthyr Tydfil CBC re the marriage and death.