Hi kilmartin,
I don't have the full ref for Jane's Brothers marriage (It was in Devon) but he was certainly a land holder. His sons and grandsons were very substantial land holders, his daughter married a substantial land holder. I did notice something with Jane's sisters marriage, who did marry in the parish. Her husband could not sign his name. Perhaps the girls marriages were not quite so good as their brother.
Thomas Trenerry of St Clements Bachelor = Margaret Martyn OTP spinster by Licence 6 Jan 1793 Crantock Thomas signed with his mark, Margaret signed witnesses Mary Martyn and Margaret Martyn (Both Signed)
The witnesses were cousins. To my knowledge there were only the three Children and parents died when Jane would have been barely 10 so guess they were brought up by other family members.
I don't see Thomas and Margaret Trennery in 1841 (Thomas was buried St Clement 28 Oct 1834 aged 69, unfortunately no sign of Margaret 1813-1837 to just see how accurate her age was) Thomas was possibly a Butcher - Sons appear to be butchers. (Of course nothing to say a Butcher would not have owned some land) I also note some of the children have the middle name Martin - Spelled wrong. Interesting, I would never expect to see it spelled with an i around St Columb Minor, Crantock but this family were in St Clement.
Guess we just hope your records will tell us a little more about the Trewarthas. As you say re those earlier marriages these men certainly appear to have some standing in the community. They left wills too which is a good sign...........Kris