You may need to check baptisms later than assumed year of birth. I have come across several in my Yorkshire ancestors that were baptised with their siblings years later!
Also, as someone else has suggested - the area is pretty close to Lancashire, and depending on the work they did they may have moved around. I have recently identified an error in the tree supplied to my uncle which ignored the census records (b Lancashire) and went down a line that was born in Yorkshire - just because the person did marry and die in Yorkshire. There was only a few miles in it, but it made all the difference to where the correct records were to be found. Lancashire parish records are available online.
