Complex sentence: And the island in Sheppey belongs to Milton;, the reference to Sheppey establishing this as Milton Regis, not Milton-next-Gravesend.
Split into simpler sentences: And the island in Sheppey belongs to Milton;. And þæt igland on Scæpyge hyrð into Middletune; the reference to Sheppey establishes this as Milton Regis, not nearby Milton-next-Gravesend.