Just to throw another spanner in the works- my father spoke to my uncle the other day and mentioned the research I'm doing, and my uncle remembered his father (Leslie)'s mother as being Susannah Freeby-Shakespeare/Freeby Shakespeare at some point (whether the Freeby is a middle name or part of the surname I am not at all sure). It's possible that he's completely off-base, but as the elder brother he has more of an idea than my father, who didn't remember any names involved. The mention of 'Susannah' was what made me consider 'Matilda Susannah Wilkes' as the likely contender. Quite how any of this is any use (if it is at all) I'm not sure, but there it is
My own searches for her under these names yielded nothing at all...
I will look into that certificate, and also I agree that possibly the Willis 'marriage' could have been more common-law than actual. It's really hard to keep track of! I must say that you've provided me with more information than I've managed in the last month (since I hit this snag), so thanks again
EDIT: My father asked my uncle today for further information, and it turns out that Susannah Shakespeare Freeby (the order was wrong) was Matilda's grandmother; somehow the two became mixed up at some stage.