I've just come across this web site as I was searching for any refernces to my grandfather. I was intrigued by your note because ...
I've just come across some papers of my late grandfather Francis Smart Fothergill ( born Ryton Co Durham 1897 ). In a brief family tree he describes Robert Swan Fothergill as his uncle on his mother's side. Apparently his grandfather a Dr Smart Atkinson Fothergill also married a Fothergill ( a cousin or half-cousin ) - although my grandfather had forgotten her name when he came to write up the family tree.
His grannie Fothergill was a great one for family history and he recalled hearing all her old stories including how Sir George de Fothergill captured York for Willim the Conqueror ( something to do with a leg of mutton ! ). He wrote that his grannie had a wealth brother or uncle called Robert Swan Fothergill who sent her to York Convent to be educated. He continued " I never met this Robert but Grandmother often talked about him. His photgraph hung in her front room and below it was the family crest, a stag's head...For a long time I used to think he was my great grandfather and not as is probable my great uncle."
My grandfather's mother was born in Paradise - a part of Scotswood in Newcastle's West End. Her family had a glue factory in Glue House Lane. She later lived in Haswell Co Durham where her husband was a colliery doctor and died shortly after WW1.
Hope this is of interest. I'm interested in anything you might have gleaned about the conjoining of the 2 Fothergill lines.