Hi Kellie I don't have a Thomas Benwell b. 1790 Reading listed yet, although it is possible that he may be related.
Since my posting I have managed to transcribe and get some more info from the Bemwell wills, and linked this in with some IGI records.
It seems that Thomas Benwell the Elder (c1656-1723 of Whitley Park, Reading) had at least 13 surviving children by 3 marriages: Marriage to 1)Hannah Creace- children Thomas (the Younger) (1674??), Grace (1685), Hannah (1687)and Ann (born?, m.1707). Marriage to 2) Susanna- children John (1693), Mary (1695), Elizabeth (1695). Marriage to 3) Mary Wilson (her mother called Sibilla)- children Maria/h (1702), Lydia (1703), Bathsha (?), Susanna (?), Henry (c1714), William (c1716).
Thomas Benwell the Elder had at least two older brothers- Henry and William. In his will, his two nephews William Benwell and William Benwell (sons of Henry and William) are mentioned a lot as they were his executors. Thomas's father was Henry Benwell (christ. 1620) and his mother was Grace (Pardis). From IGI records it seems that Henry Benwell's father was William Benwell (chr. 1581), and William's father was another Henry.
As you can see from the census, there weren't that many Benwells around. Because of the name (Thomas) and place (Reading), your Thomas Benwell could possibly be a descendent of Thomas Benwell the Elder. This could be via one of his four sons (Thomas, John, Henry, Willam). His son Henry (c1714, my 'line') had sons called Henry (1742), Thomas (1747), John (1749 -my 'line'), William (1753, d. 1754), Joseph (1756). So far I haven't traced descendents of the sibling lines but will let you know if I find anything.