Thank you for your reply. Your James does not as far as I know connect to my family but another Langdon family landed up in the same village as some of my Langdons. I have not been able to connect the two families. All I know about this family is that the 1871 census shows a William Langdon with his wife Mary A living at the Smiths Arms in Langore near Launceston. His parents were John and Jane Langdon. He was probably descended from James Langdon of Ruan Lanihorne near Truro.
However, I do have a photo from a studio in Plymouth and have no idea who the lady shown might be. I would be happy to send by email if you would like to contact me direct: a.a.neuner@gmail.com.
If you are able to find the Barnstable research I would be most interested as this is exactly the Devon area that I am trying to connect to.