Thanks for your reply.
I know it's so annoying about these missing registers. I had a researcher working on this but he couldn't conclusively tell if it was the right William or not. We did think about looking at wills but there didn't seem to be any suitable ones, although there were 29 just for Ekins in Raunds apparently.
I'm back as far as William BLACKWELL and Elizabeth WHEATLEY too. There are BLACKWELLS in Benefield and Clapton/Clopton but I am not 100% convinced that they are ours yet, mainly I think because they sound too good to be true. How far do you go with the BLACKWELLS? Mine go to Sarah BLACKWELL who was my 2 x GGM