Hello,
Thank you for replying and looking up some records!
Unfortunately James Ching was born in 1855, his age is listed as being 34 in 1889 on the marriage bann. One of the witnesses was called Peter Chungting who married a woman called Emily.
On another forum for Liverpool history someone related to Emily found the below, her family had links to Singapore, I think her mother gave her occupation as relating to Chinese interests.
Peter Chunting, steward, full age
Marriage Date: 5 Jan 1884, 141 fredrick st?
Parish: Liverpool St Luke
Spouse's Name: Emily Moitt, age 19
Father's Name: John Chunting, Chinese Governor
Spouse Father's Name: William Henry Woitt, steward
From the same forum "1891 census at 13 Liver Street RG12/2910 f88 p18 ( which doesn't seem to be aviailable on Ancestry):
Peter Chung Ting head 45 Ship's Steward, China
Emily do wife 24, Litherland
Ahlan do daur 3, Liverpool
+ 4 chinese lodgers "
So it seems that the link is Chinese rather than Devon. I've still failed to find any trace of them , I wondered if they changed their name to something easier. James Ching does come up on some New York records as crew and passengers so perhaps they did migrate. It's odd that no one else I am related to has picked up on this at all though.