I think that Thomas was baptized at Ashprington, Devon on 14 March 1737; his parents were Thomas and Sarah Parnell. He married Ann Tozer in 1765 at Stokeinteignhead, a small village in South Devon. Thomas signed his name on the Banns whereas Ann could not write and made a mark.
Below is a modern photograph of the village – but I expect it was quite different when Thomas lived there in the 1700s!
Stokeinteignhead