As you can see, Catherine William (born 1772) was reported as living at Bonyraer at the time of her death in 1822.
This John William may have married Mary Lewis after the death of his previous wife, Catherine. Our John Williams would have been 25 at the time of Catherine’s death, whereas she was 50. Of course, Catherine could have been John William’s mother. But then our John’s mother was Margaret.
My conclusion: The marriage we have assumed to be that of John Williams and Mary Lewis on 1st March 1824 is the wrong one. More research was required!
Since the initial research was carried out a lot has happened in the world of genealogy. Many more records are now available online. Mary Lewis was from Llanbrynmair, Montgomeryshire, so let’s search there. It turns out that a John Williams from Towyn, married a Mary Lewis from Llanbrynmair on 15th May 1827. This is the record we have been looking for.