Dear Kath,
I presume you mean the line back to Wimarc? Yes, we have that through to Yorkshire in the 1600's, but our earliest Exelby, a merchant taylor of London, is just said to be of Yorkshire, and the actual family there he is from isn't mentioned.
Have you ever seen the book of the Exelby family by an Eshelby, written in the late 19th century?
:)
Tracey