Symphony 46, Op 311 - III. Nimrod presso la fortezza

A composer associate once told me that the enigma that Elgar posed to all of us in his "Enigma Variations" was a counter melody to a well-known tune. In our discussion we talked about a theory that Bach/Luther Hymn, "A Mighty Fortress" was the source. It works if you Play the two themes at a 3/2 ratio. Curious.