Nimrodel of Lorinand
Tolkien was rather insistent upon the fact that his work was not allegory, but rather a mythology created for England.
When you get into the Lays of Beleriand, you read about how the Eldar interacted with the people of Great Britain, and how the isle of Britain itself was connect (not in the literal sense) to lands far to the West (Valinor, etc). I recall something about Ulmo trying to pull an island back and it didn't work; the island broke and the part Ulmo was left with became the British isles...