Well, I found this:

Utah Phillips tells the story of Eddie Belkowski, a brilliant young concert pianist, who lost his right arm fighting with the Lincoln Brigade against the facists in Spain. In the hospital he became addicted to morphine and wound up a derelict in the streets of Chicago. Thirty years later, fighting to recover his lost life, he was working as a janitor in a nightclub in Chicago where Utah was performing. Late one night after the show, Utah said he heard the most beautiful piano sonata coming from the main room after everyone else had gone home. He looked in and there was Eddie Belkowski, all alone in the dark, playing Chopin with his left hand!

from: http://www.autoharp.org/archive/v12.n012

Maybe it's a Utah Phillips song......???