I wonder if it is possible to try and find Thomas Wilcock and Ann Dinsdale, with the 3 children (Mary, Hannah and Elizabeth) listed in 1841 and 1851 census.
Might be worth putting up a separate query for them.
Just to follow them through and see what happens.
Even though you do not have a birthdate for the couple, someone might be able to find something through the children.
Unfortunately I do not have access to the census.
I did have a thought

, that perhaps, Thomas (1799) was illegitimate and they baptised him in a different church so that none of the 'locals' new.
Not sure if they could get away with that and it would be hard to prove anyway.
One of my wayward thinking ideas

What are the names of your Thomas' children?
Margaret