Hello,
Just as a follow up to William Sadler, there is a marriage recorded in the parish of Tintern, which is adjacent to Trellech, on the 14th August 1816 between William Sadler a bachelor of the parish of Trellech to Hannah Young a spinster from the parish of Tintern. It is a possible for the marriage as the date is ok and bearing in mind people often used variations of their name on census', hence Hannah, Anna or anne.
Best of luck,
tallpaul.