It would be wiser to wait for the birth cert before doing any more searching. We are already on page 6 of this post and are not yet 100% sure which family we are tracing.
All we know for certain is that the 1840 marriage certs shows father as William occ Corn Meter.
However - until the birth cert arrives we don't know whether that is even the right marriage.
Indeed, i am very impatient and as i am with many brick walls with the amount of time i have spent doing my family tree it never seems a waste of time even if it is the wrong family. There is someone with a tree on Ancestry that puts it altogether nicely, and it looks to work on my line of thinking also;
They have;
William Overall (the CornMeter by the looks of it) Born 1785 to William Overall and Sarah Hart.
he has two brothers John Overall 1789-1842 and James Overall.
My (Possible) William Overall's brother John Overall, married a Frances Hammenden and had;
Frances (1815-1867)
John William Overall (1818-1898) - The gentleman i incorrectly believed to by my John.
Ann Overall (1822)
Mary Ann Overall (1823)
Then he has John William Overall (1818-1898) marrying a Sarah Standerwich and having 12 children, two of which he has pictures for on his tree - (usually indicating it's his direct ancestry). This would make me think that he has confirmed the Sarah Standerwich marriage.
Obivously i have spent the £9.25 on the certificate now, but it seems to point to Sarah being a Butcher as it stands.