Complex sentence: King Offa had a church built in Offchurch (hence the name'Offchurh' coming from'Offa's Church') this church has since gone but a church has been rebuild on the supposed site of Offa's church.
Split into simpler sentences: King Offa had a church built in the village (hence the name "Offchurh", which comes from "Offa's Church"). This church has since gone, but a church has been rebuilt on the supposed site of Offa's church.