thanks, I appreciate this
It looks like John had two more children I was unaware of, John and William
I have checked the census, but I cannot seem to find them, nor their child Francis, whom hasn't appeared on the census, though a baptism record exists. He may have died young, perhaps before the 1841 census.
It's no problem if Francis had his name written erroneously, it was definitely Francis.
Interesting that the family are living in Durham, quite a distance to travel, especially since all subsequent census entries give them as living in Byker. John is last seen on the 1881 census as an invalid