Wally
Marriages before 1 July 1837 did not have parents names, unless they were under age and required their permission, in which case the name of the father or mother giving permission would appear.
If your library has Ancestry then you can access this marriage via the LMA records on there, and see the actual images.
There are a number of Henry and Sarah SMITHs baptising children in the area at that time, so your 3G grandfathers baptism should be there as well. What was his name.
Ian C