These notes from Larrikin 001 "Man of the Earth":

"Song of the Thrush: It was a common practice for British miners to take a caged thrush or canary down into the mine with them 'to test for bad air'.'The song of the thrush' was written in retrospect by George Le Brunn. The pure sentiment expressed in the song is typical of the music hall songs of the mid eighteen hundreds."

Dave de Hugard was to sing the song on this album...he thought it might work better as a poem, so he sang the song through 'just to get the feel of it'. Head Larrikin Warren Fahey tipped a wink to the engineer and the tape rolled as Dave tried the song out, singing softly in a very relaxed, non-performing style. And that's the version that was released, back in 1975.

...as far as I remember !

Tony in Darwin