Thankyou very much for your reply, I am not a relation of Ralph’s but rather have been researching him for academic purposes, focused mainly on the mariners compass that he designed in the 1790s.
I wonder if you have read his nephew James Walker’s memoirs? They are Accession no. 53 at the Institution of Civil Engineers, and contain some very interesting and detailed information on members of the Walker family, including Ralph and his wife and children. According to this, Ralph married a Miss Wilson in Ireland; I combined this information with the name Jane given on Charles’s baptism record, and haven’t come across the name Clifford anywhere.
It would be great to hear more about what you know, and I’ll help to fill in any gaps of yours if my research so far covers them! My email address is hannahsalisbury1 (at) gmail.com.