Thank you slowhands, I knew you'd come up with the most logical answer. I notice that a Mary Toomey married Thomas Barnard in the same year, at Churcham. And there is also a Richard Toomey, 1787 a base son of Mary - possibly the same Mary Toomey. I don't know what happened to Richard and I can't even prove that Benjamin's mother married Thomas Barnard.
Thanks again
Steve