The 1851 census for the township of Rhysnant (Llandysilio - Four Crosses between Oswestry and Welshpool) shows a Roberts family (Thomas being a G,G,Grandfather):
William, 63, Head, Boatman;
Elizabeth Roberts, 58, wife;
Thomas Roberts, 22, Boatman;
Richard Roberts, 14, Boatman;
Joseph Judar[?], 8, Grandson,
Though I don't know anything about their life.