Still nothing. Let's narrow things down a bit more, shall we?
Clue #1: One songwriter.
Clue #2: One of the longer tracks on its respective album.
Clue #3: Played live by more than one lineup.
Clue #4: Mr. Murray
Clue #5: It has appeared on an official compilation.
Clue #6: Despite its appearance on the tour of its album's release, it was dropped from the setlist of the band's next tour.
Wrong Guesses: Empire of the Clouds, Flash of the Blade, Cross-Eyed Mary, To Tame a Land, Fear of the Dark, Mother Russia, Phantom of the Opera, The Clansman, Powerslave, Charlotte the Harlot, Rime of the Ancient Mariner, Sign of the Cross, Strange World, The Clairvoyant, Afraid to Shoot Strangers