Can we just confirm what you actually have?
You have christening of Edward in 1801 in Basford , parents William and Ann.
Do you have christenings of any other children of William and Ann?
You have a marriage of a Sarah to Gervas Greasely in 1798. How do you know she is Williams sister? Was she a spinster at this marriage - ie was Leighton even her maiden name? Where have you seen her pace of birth as Basford?
Have you found christenings for William and Sarah with same parents?
When William fathered Edward he could have been anything from 16 to 90. So if you don't know if Edward the first child of a very young couple, or the youngest child of a couple who had been married 20 years, or even of a second marriage for William, then it is risky to "guess" how old William was at this stage, without finding out some more. And, as has been said, there is the question of where William may have been born - very unusual of Edwards christening showed the place of birth of his father! (very useful if it did)
