I've finally found a website that allows me to see a little bit of information without having to pay and it seems that, by 1851 William had 16 acres and was listed as a farmer as well as a mason and while presumably, not rich, not poor either. That fits nicely as books were comparitively expensive in those days and those on low incomes couldn't afford them, even supposing they could read in the first place!
I've been trying to see if I can find out what Anne might have been doing in 1841. She might have left home and been working, but she could also have been visiting relatives. With my very limited options, the only record I can find that might possibly fit is an Ann Sharp shown on the 1841 census as living with a family called Braithwaite in Workington. No wife has been shown which suggests he's a widower. He has four young children aged 9, 8, 6 and 3, so presumably would have needed a housekeeper to help look after them.