John Boorman, who directed both "Zardoz" and "Excalibur" was actually in the planning stage of directing an adaptation of LotR.
Interesting stuff about that on the "Excalibur" IMDB trivia page here:
http://www.imdb.com/title/tt0082348/...ef_=tt_trv_trv
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John Boorman was originally aiming at making a movie based on "The Lord of the Rings". However, he did not acquire the rights, and decided to make this movie instead.
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The trial by combat set in the woods was originally to be the set for the Rivendel counsel chamber in John Boorman's version of "Lord of the Rings", which failed to get made.
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Boorman originally wanted to direct The Lord of the Rings, but Ralph Bakshi secured the rights first and beat him to the punch. He settled with this as his Plan B, another medieval sword and sorcery epic swashbuckler.
and on Boorman's IMDB page here:
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http://www.imdb.com/name/nm0000958/b..._trv_sm#trivia
[on his failed attempt at bringing writer J.R.R. Tolkien's "Lord of the Rings" to the screen] Everything I learned, the technical problems I had to resolve in planning for "The Lord Of The Rings", I applied to Excalibur (1981). That was my recompense.