This is a long time after your original post and my information may not come as good news.
John Fletcher (b1766) later called himself John Fletcher Wilkinson. (The Fletcher may be after his executor Sir Henry Fletcher, or may give a clue to earlier generations). Having been awarded a Doctor of Divinity he was chaplain on St Helena until 1808 when he resigned in something of a huff after a teacher was appointed on the island. Returning to London he was clearly well-off as this court case shows:
https://www.oldbaileyonline.org/browse.jsp?id=t18120115-71-victim756&div=t18120115-71#highlightHe died in 1828 and his PCC will leaves everything to his surviving siblings or their descendants. He names Lucy (dead), Mary (dead), William (dead), Sarah and Barbara. Rather touchingly he says he doesn't expect any of them to come down from Cumberland for his funeral!
The money wasn't paid across so there was a court case (1835) which names several of the children including Mary WORKMAN's children and William's children Peter and John. They may well be the Peter (1800) and John (1796) born to a William and Mary Wilkinson, but I hope I am wrong and that William and Jane also had those children and that your William died before 1828.
Some years ago I wrote about Lucy and John Wilkinson here (it may need updating):
https://www.64regencyancestors.com/mingings-and-birdApologies of this brings bad news. I can give you more details about the court case if you want.
And thanks for the information on John Sr as I didn't know he was a miller.
Richard
