Thanks for your reply.
I'm deeply suspicious of the link back to Parham, sadly, as I think I've said earlier on this thread.
I did have note of a John Mayhew born in Walpole in 1717 who sounds a more likely next generational step going backwards; but I can't at the moment find the source for this - it didn't come up on a search of ancestry and familysearch.
Have you seen John's will (made 1814, `proved' on his death in 1823)? It refers to 10 children, with quite a lot of detail. I could post a summary here or email it.
Denis