Hello JanW,
Would the name of your ancestor be John Nield?
I have him in the 1841 census in Mickle Trafford, age 40 and occupation Blacksmith.
I don't know of a blacksmiths at Mickle Trafford offhand. The best sources of information regarding this would be either the local Township pack on Mickle Trafford, or the book on Mickle Trafford in the local history series. Both of these can be found in the Cheshire Record Office, or libraries in Cheshire. Chester library has a good stock of them in particular.
It could have been that he lived in Mickle Trafford but worked elsewhere. I know there was at least on blacksmith in Kelsall, not too far away. My ancestor was one of these in this period.
Jo