Marriage lookup - St Marys, Reading

[KPM]

Can anyone help me remove a brick from my brickwall?
I am trying to ascertain whether William Long, who married Sophia Lewin at St Mary's, Reading on 13-6-1815, is actually my ancestor.
I know that the parents of my relative, were William and Sophia, but all the children were actually born in Kingston, Surrey.  The only marriage I can find between a William and Sophia is the one at St Marys.
I am hoping the Parish registers may be able to give me a clue, perhaps a witness?
Any info would be really appreciated