I don't have any certificates for these folks, I'm afraid. My husband's tree goes through William's brother ROBERT, so I can tell you some more about William's siblings, parents and grandparents if you haven't got this.
We still live in Essex (Braintree), which is about 10 miles from Castle Hedingham, so we haven't moved that far! Where are you? If you need help getting a reference for a certificate, I sometimes get to the Essex Family History Centre (not very often, thanks to the kids!) so could do a look up for you.