philipsearching you say this is most likely to be him -
Jun qtr 1838 Birmingham vol 16 p337 ASTON William - no mmn.
but there are possibly 6 who might be him.
Dec 1838 Wolverhampton (I don't know whereabouts in Birmingham area he was born - I am presuming most likely to be Birmingham area but could be outlying districts)
March 1839 Birmingham
June 1839 Birmingham
Sept 1839 Kings Norton (Joseph Twist has some connection with Kings Norton, not saying he was the father but maybe that is where he met Emma)
Sept 1839 Wolverhampton.
So unless I can find him with a mother named Emma, who knows which one he is, or if any of them.
I'd settle for finding the birth details of his older brother John if I have to accept I will never find any more details going back on William.