David - I think things might be about to become a little more complicated for you!
And I suggest it might be a good idea if you were to find out a little more about Thomas Treloar and his descendants before you spend too much time looking for his baptism and parents.
As there is a Trewhella involved I decided to have more of a look at Thomas before going back to the project I have been working on.
The first thing I did was to check for other children of Thomas and Catherine Treloar and I immediately became a little suspicious when I discovered only two more baptisms to this couple:-
Elizabeth daughter of Thomas and Catharine Treloar baptised 18th November 1781 Marazion
Elizabeth daughter of Thomas and Catherine Treloar baptised 23rd October 1782 Marazion
I have not yet found a burial for the first Elizabeth so this 'might' be a case of a private baptism with the public baptism coming almost 12 months later - but I think I will keep my mind open on that.
Now to find just two (or three) children in the space of two years after a marriage and then nothing is most odd and my first thought was that either Thomas or Catherine may have died. We know the family remained in Cornwall because their son Thomas married in 1804 so this seemingly minor detail opens up a whole new scenario that might impact on your thoughts about the parentage of Thomas.
My next search on the OPC site was for children of 'tho trel' between 1780 and 1800. This gives a list of all children within that period to anyone whose forename and surname beings with 'tho' and 'trel' so there is a little 'weeding' to do. The items of interest produced from that were:-
Benjamin son of Thomas Trelower baptised 29th January 1786 Gulval
Hannah daughter of Thomas Trelower baptised 17th August 1788 Gulval
The next entry of interest to myself was:-
Henry son of Thomas and Sarah Treloar baptised 28th January 1793 Ludgvan (born 7th January)
This last piqued my interest because Ludgvan and Gulval are adjoining Parishes and because there are later events for Thomas Treloar's family at Ludgvan. And I was even more interested when I found this:-
Catherine Treloore of Gulval age 31 buried 17th July 1787 at LudgvanI should note at this point that I could find no other marriages to account for the baptism of Benjamin Trelower at Gulval in 1786 so I suspect he is another child of Thomas and CAtherine. But I did find a marriage to account for the other two children:-
Thomas Treloor and Sarah Noal married 1st January 1788 at Gulval
There is no indication in the marriage record that Thomas Treloor was widowed however I have compared the signiature of Thomas with that of Thomas Treloar when he married Catherine Thomas. In both instances the surname was signes as TRELOOR and the handwriting is practically identical!
Returning to the above burial of Catherine Treloore at LUdgvan in 1787 - this fits with what we already knew about Catherine and Thomas and it also suggests that Ludgvan may have been the 'home Parish' of Catherine. As her age (31) was recorded there may be a good chance of finding her baptism at Ludgvan. A search of the OPC database offers just one possibility:-
Catherine daughter of William Thomas junr baptised 24th June 1756 at LudgvanI would suggest there is a good possibility this is the wife of Thomas Treloar especially as a Wm Thomas witnessed the marriage of Thomas and Catherine!
My view of the family now looks like this:-
Thomas Treloar and Catherine Thomas both of the Town of Marazion married 16th January 1780 St Hilary
Thomas son of Thomas and Catharine Treloar baptised 15th September 1780 Marazion
Elizabeth daughter of Thomas and Catharine Treloar baptised 18th November 1781 Marazion
Elizabeth daughter of Thomas and Catherine Treloar baptised 23rd October 1782 Marazion (possibly same child as above)
Benjamin son of Thomas Trelower baptised 29th January 1786 Gulval
Catharine Treloore of Gulval age 31 buried 17th July 1787 Gulval
Thomas Treloor and Sarah Noal both of Gulval married 1st January 1788 Gulval
Hannah daughter of Thomas Trelower baptised 17th August 1788 Gulval
Henry son of Thomas and Sarah Treloar baptised 28th January 1783 Ludgvan (born 7th January 1793)
If correct then it certainly puts a different perspective on the family and offers more clues to the identity of Thomas Treloar.
Something for you to think about.
CT