Adding this in the hope that someone can clear up confusion around the source. Wikipedia currently says this was published in 1887 in ‘Truth’, Sydney. However, that paper was founded in 1890. I cannot find the poem in the Bulletin (which Henry did write for).

I did find (in Trove) a mention of this being sung as ‘The Flag of the Southern Cross’ prior to 1887, but no other details (and maybe not even the same song).

Any wisdom appreciated.