Hello, I am not a font of information on the subject, but could we be thinking Scottish provincial silversmiths? For the "WC" we have William Clarke of Greenock whose mark is shown as in an "ovalish" cartouche, William Constable of Dundee and William Craw at Canongate. Interestingly William Craw may have been in a Canongate "C&H" partnership with James Hill (Circa 1770-75) and you could fantasize that Mr Hill could have been in an earlier or later partnership with a "D" surname silversmith. There is an Alexander Drummond referenced at Canongate circa 1760.
There is a forum post that mentions William Craw and suggests he did not always use additional pictorial marks.
https://www.925-1000.com/forum/viewtopi ... ngate+craw
I have done plenty of speculating so I hope there is information to come from others in the Forum.
Fishless