Dunwich !.. lots of spooky stories in Suffolk. It must have been a hub of activity there, as the Domesday Book records 3 churches and 3000 people. Reading your link, it mentions Walton Castle in Felixstowe. I lived there for 12 years and have to disagree with the information on Wikipedia.
https://en.wikipedia.org/wiki/Walton_Castle,_Suffolk
They say that Walton Castle was in Walton, Felixstowe. They also say it was in Old Felixstowe, which are two different areas.. The image they show of the cliffs at Felixstowe is in Old Felixstowe. I have seen the ruins of Walton Castle from that very point on one occasion, when the tide was very low .
St Felix is still around and about Felixstowe on plaques and posts. Oh ! and they all hear bells in that part of the world !
Which brings me to think that maybe one day the submerged church at Moreton might become visible.
Thanks for the other links.