Barton Mills baptisms are on familysearch - all there is for Smith is:
William bp.27/3/1796, son John and Elizabeth
Ann bp.13/10/1799, dau. John and Elizabeth
Mary bp.28/12/1800, dau. John and Elizabeth
There are no more Smith's 1801-1816 then 3 1817, 1818 and 1820 the latter being a James bp.29/2/1820, son of Robert and Eliza.
Annette