To answer CET from 20 years ago (!) I think I said this before but MacColl picked up the phrase 'Big Hewer' from his time with the Elliotts of Birtley in 1960. His vist resulted in the Folkways (cardboard cover) LP of the family songs.
The Big Hewer was a legendary figure in Durham with legendary powers- reflected later in MacColl's song. Jack & brother Reece had stories about the Hig Hewer probably too earthy & not literary enough for inclusion in the later song.
One story was that the BH had a huge appetite & would eat six chops while waiting for his dinner. Also if he was hungry while down the pit, he would just pull out a few steel rivets from a coal tub & chew on them.

I make no judgment on MacColl's song (there be dragons) but if you have a genuine interest in songs of the Durham miners, you'd do better listening to the Elliotts instead.