Roll back your minds and bring out your VCR. Looking for the name and lyrics for the song in the movie "Trainspotting" which is sung (by the character Spud) after the passing of their friend Tommy. The last line in the song is "...when we were little boys."

I heard this song many years ago, I believe it's a traditional celtic song. Anyone with any help or suggestions?? First answer get a surprise... well, maybe?