Don't know if you found your Dunkley's in 1841 census. Found the following for Bradford, Yorkshire.
John Dunkley. Head aged 40. Woolcomber. James. 14. Ann.20. Family living in York St, Bradford. John possibly a Widower. -- I checked Cornelius in the 1841 census born c.1835. Father John Mother Sarah. I see that Cornelius's father John was not a Widower acc to 1851 census.
I checked deaths for Bradford from 1837-1841 for any deaths in Bradford and found only one thatcould be John Snr's wife. Her name was Sarah Ann Dunkley. Death 1840. Possibly mother of James born 1827.