Thanks for that, Willow!
I'll keep a note of that. I still haven't found out about Agnes Jenkins's origins, but I suspect it may have been Flintshire, Denbighshire, or possibly Shropshire. She married Thomas Martin in St Mary Marylebone in 1802.
Doesn't sound as though there is a connection, but you never know. I suspect she may still have had relatives there in the latter part of the nineteenth century.
Marie