Hello,
In Richard Fothergill's "The Fothergills - A First History" he writes:
"Many Fothergills lived in Mallerstang, almost certainly migrating over Wild Boar Fell into the valley. It is probable that the early residents would have been younger sons who would not inherit the tenancy of their parent's farm, but who had sufficient determination to develop a new piece of land in their own right."
I don't know whether or not you know the geography of the area but in case you don't Wild Boar Fell is between Ravenstonedale and Mallerstang.
He then has about 64 A4 pages about the Fothergills in Mallerstang with quite a few family trees but I've had a quick look and can't see your John Fothergill.
This book was followed by "A Second Family History" in which Richard Fothergill published his further research along with information that came from other Fothergill members after the first book was published.
I think you would find
www.ravenstonedale.org intersting but then you probably know all about it already.
Good luck with your hunting
Brie