Birmingham twice recently, I have only just heard of the Middle Earth Festival, which prompts me to make a comparison:
whereas Tolkien's Lord of the Rings Trilogy is part of his Middle Earth series which recounts a fantastic past history of Earth, Poul and Karen Anderson's The King of Ys Tetralogy is one part of Poul Anderson's complete works which recount past and future histories in multiple timelines;
both The Lord of the Rings and The King of Ys explain how our prosaic present has followed from a fantastic past - Earth became round and the elves withdrew, Ys was inundated and its memory suppressed;
I have read ...Rings twice and ...Ys three or four times;
I prefer Anderson to Tolkien.