G'day,
Just thought I'd paste this from one of my earlier posts in this thread:-

Peter and Chris Coe's "Open The Door And Let Us In" album whose sleeve notes say of "The Gay Fusilier": A recruiting song set at the turn of the 18th century. Peter found the first verse and directions for the tune (said to be originally English) in a magazine, but after searching unsuccessfully for the rest of the song, he wrote the additional verses himself.

However there appears to be no sign of this song before the Boer war, which was strongly represented by Aussies. If it did exist before then it could easily have picked up the Matilda tune at that time. (See earlier posts).

Cheers,
Alan