[The Squatter of Amon Rûdh]

The story of Númenor and its fall are inspired, at least in part, by the legend of Atlantis. To the best of my knowledge Tolkien intended no reference to the British empire, although his opinions about imperialism in general are clear from this extract from one of his letters, written not long after the German surrender in 1945:

Though in this case, as I know nothing about British or American imperialism in the Far East that does not fill me with regret and disgust, I am afraid I am not even supported by a glimmer of patriotism in this remaining war. I would not subscribe a penny to it, let alone a son, were I a free man.

(at the time Christopher Tolkien was serving in the Royal Air Force).

In another letter he said

For I love England (not Great Britain and certainly not the British Commonwealth (grr!))

In this case at least the great island nation that founds an empire owes more to Plato than twentieth-century geopolitics.