The name Cowpen is not an easy one to explain.
I have to refer to information in John Wallace's book The History of Blyth.
Before Richard the Lion Heart left for Palestine in 1190, he granted 'Copun' to monks of St Oswin's.
Wallace stated that 'Cowpen' has been a place of importance since Saxon times.
He mentions "couping" which was an ancient form of bartering, or exchanging one commodity for another.
A Salt Pan was granted at 'Cupun' by King John in 1201. Also mentioned was the 'Cup-well'.
In 1240 "Cupun" was accounted in the Barony of Bolam.
About 1240, James de Bolam granted the canons of Brinkburn Salt Pans at 'Cupun' which involved the Bishop of Durham.
By 1307, Brinkburn and Tynemouth Priories had Salt Works at 'Cupen'.
By 1428 it was 'Coupowne'
By 1560 they were spelling it 'Coopon'
By the 19th Century it was 'Cowpen'.
Additional information, it is not a Pen in which to put Cows! Hehehe. I made that mistake myself.
It is also believed that the name 'Cowpen' might originate from an Old Norse-Scandanavian word 'kupa', which means cup or bowl. The word is also used to describe a cup-like depression or valley in the ground, and this might well make reference to the earliest saltpans in the area or perhaps the lay of the land. The word 'kupa' also has connections with the Swedish 'kupa' meaning a small cottage or household. So both phrases 'at the hollows' or 'at the cottages' have relevance.
In reality, no-one can say for sure now, where the name originates.
I hope you have found it interesting despite being no further forward after reading that little lot.
P