Are you in Swansea? If you are , go to the library in Mumbles they hold a lot of snippets of records/information there with some of the history of mumbles. I have a few who were on the lifeboats, and one who was captain of the lifeboats for a time ( the librarian found a record for my mother -in-law , who lives in mumbles today , for him), another ancestor had had a pub there, but most were mariners, farmers/landowners in the area , and oysterdredgers . I'm really getting the furthest with my Husband's Oystermouth/mumbles lines because of the amount of history that area seems to hold, plus the small size of the area.
My husband's mother who was born in oystermouth , her fathers side come from Oystermouth on both lines. A few of those lines ,we have actually gone the back the furthest so far to a family called the bydder's in the 1600's in Newton . I'm finding Oystermouth and mumbles area one of the easiest to research. I wish my own family came from there
. My husband is lucky with his tree and oystermouth families.
If you are not in the UK, no worries, there are other means. Mumbles holds a lot of history, and you could also try emailing "the Mumbles book" web site and ask them for some info/help, you may get lucky. It may be worth a try.
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There is a J Thomas lighthouse keeper (* but it's 1900's)
Mumbles
Pre-1841 Glamorgan Oystermouth The Mumbles light was established by the Swansea Harbour Board, and not taken over by Trinity House until after 1901
1841 Ace A (G'father), 1851-61-71-81 Ace A (Father), 1891 Ace A (Son), Morgan H, Williams J, 1916 Cottle C, Thomas J
http://www.genuki.org.uk/big/Lighthouses/LighthousesStations.html..................................................................
Thomas,John,Mumbles Lighthouse Keeper,1916,36
The above is from a book called "The men of mumbles head " I'm trying to get hold of the book myself (it's out of print, and I can't visit the library I'm not in the UK) my husband's G, G granddfather is in there "John Parker" lifeboat crew, and a few others too.
http://www.genuki.org.uk/big/wal/GLA/Oystermouth/Mumbles/MumblesLifeboat.html(
http://www.themumblesbook.com) may be some use to you as well
There is a John thomas in the 1841 census c1781 , occupation Mariner, oystermouth, Ann C1871 and Thomas c1831 ( which matches the son Thomas's age that you've given) in one household ( the other children could have left home by 1841) a lot of those lighthouse keepers were mariners before and after. No address sorry, it just says Mumbles village
There are not lot of people with the surname Thomas in Mumbles village in the 1841 census ( 26 people in total that I found with my search )
There is a Martha thomas who is a servant age 15 ( working at another house) c1826( which seems to match your Martha's age . There is only one Martha Thomas in Mumbles in 41. There is also William c 1816 and this william's , occupation is also mariner. He is living with a Mary Thomas , occupation housekeeper c1776 . It dosen't say the relationship in the household, so there is no way to tell if this is his mother or his Aunt )
Marianne , Walter and Jane Thomas I can't find those names in Mumbles in 41 ,the girls may be there somewhere under their new married name. The rest of the boys "David' may have moved out of Mumbles , or maybe out at sea on census night, or even died
Could be yours, may not be either. But the ages seem to be matching up. So it may give you something to check up on.
It may also be worth you doing a search in google with the persons name , and the word Oystermouth or Mumbles, it can bring up some results that may be relevant to the family you are looking for.
Hope that is of some help to you.