Hmm. Marriage registers do not record place of *birth*. The place of abode (an address, sometimes, after 1837 but otherwise a parish) refers only to where the person was living in the four weeks prior to the marriage.

As you say, there were some WILLIAMSONs in Mappleton in the 18th century but they seem to have moved on before John was born at the beginning of the 19th. They probably didn't go far, as John was close enough to court a girl living in Stanton and was presumably living and working in Mappleton in 1820.

Which other registers have you searched for a baptism that might be his? Logically, your best bet is to work outwards in concentric circles, parish by parish. The difficulty, however, will be in identifying which John WILLIAMSON is yours. It would be imprudent to claim the first one you find. So you will need to make a note of all that you find, plus other WILLIAMSON events in the registers, to try and build up a picture of the family groups. You will then need to trace these families forward in the hope of either finding corroboration that one of the Johns is yours or, if that fails, eliminating the other candidates.

Another possible scenario is that the WILLIAMSONs took up with a non-conformist group around the turn of the century but stayed living in Mappleton and that this is the reason for the lack of later baptisms. Have you checked the marriage registers for the early 1800s? The law required marriage in the CofE at that time, irrespective of denomination.

Hope this helps

Caroline