Interesting thread, been meaning to start a similar one for some time. Of course stuff like our player-related songs are easily identified (Scotty Arfield - Saturday Night, Germain Defoe - Hey Baby, etc), but there's a few more Loyalist ones I'd like to know the origins of.
The Sash is an interesting one, because I think it's original, but the tune used to sound quite different when it was first written in the 1920s. Some flute bands still played it that way in the 50s and 60s.
Derry's Walls - God Bless the Prince of Wales.
Billy Boys - Marching Through Georgia (though there's also a version where the verses are sung to the 18th c. tune Ye Sons of Albion).
Follow Follow - I Will Follow Jesus.
No Pope of Rome - Home on the Range.
The Bouncy - Cock of the North.
The Protestant Boys - Lilliburlero.
I Was Born Under a Union Jack - Wandering Star.
Father's Advice - Fields of Athenry.
Crossmaglen - mentally challenged version is the original.
Will You Stand - a mentally challenged song about Bobby Sands.
Copland Road - old Scottish tune (can't remember the name just now).
Four Lads Had a Dream - Sloop John B.
Flute for 50 Pence - John Hark.
Heroes of the UVF - Glory Glory.
C Company UVF - Beautiful Sunday.
Not sure if We're Coming is related to the Tartan Fanny Army's We'll Be Coming?
A lot of tunes also reuse the same tune, eg. "Gibraltar" is pretty much just "The Old Orange Flute." Anyone else noted that Hearts' "Hearts Song" is also actually just "The Old Orange Flute?"
One I've always wanted to know is the origin of Number One Platoon, I'm convinced it's a pre-existing Irish song. Would also be interested to know the origins of King Billy's On the Wall and Build My Gallows. Here Lies a Soldier also dates back to the 70s but not sure if it's original.