Dear Haydn,
I found a record of Evan Evans Marriage. It took place in Christleton on 5 May 1829, when I think Sarah was 41, having been born in 1788. She died in Ince, where EE was Curate, in 1847. He's listed among the Vicars of Ince from 1843 to 1852. So they couldn't have had a child in 1817, as Cory thought.
Cheers, Valerie