If you know the name Procol Harum, it's for their massive 1967 hit Whiter Shade of Pale. But no one-hit wonder is this group; they've put out an impressive number of albums and there's no shortage of good stuff.
This is another situation where you load up your entire music library into a media player, hit random, and see what happens. This is also another situation where I had forgotten about this band (and especially this song) until it came up in the queue. Either way, great song from a great album.