Hi,
Not saying that this is definitely the marriage, just making suggestions.
However on 1851 Census, Mary gives her age as 77 so born 1774, the census was taken on 30th March, there is a Bpt for a Mary Whitehouse, dau of Joseph & Mary Whitehouse 9.4.1775 again at
Harborne St. Peter’s. This would match exactly with the age of 77.
On opposite page, there is a Bpt for Hannah Whitehouse 25.4.1774, with same parents.
Did any of her other children have second name of Whitehouse?
Spendlove