Isabella Sewell - Kendal

Searching for Birthdate/Parents/Siblings of Isabella Sewell, believed born in the area of Kendal, Westmorland in the late 1700's. It is thought her father was Henry Sewell but this is not yet proven.
She married John Smith of Kendal at the Kendal Parish Church on 24 December 1797.
The Smiths eventually settled in Ashton under Lyne, Lancs., where John died in 1846 and Isbaella in 1863.
Can anyone find the record of a marriage between Joseph Sewell and Isabella Latham on 13 Sep 1769? It is an entry on the LDS Family Search site but shows no source for the information (other than the LDS ceremony of Sealing).
All help gratefuly received!