G'day Guest,

The "Cockatoo" of the song ( ... and vernacular of the 19th century, in & around Australia ...) was Cockatoo Island: in the Parramatta River just off Balmain & Birchgrove. That is, nowadays, the River, i.e. west of the Harbour Bridge and all the way to Parramatta, while Sydney Harbour is the area east of the present Bridge - and all the seven kilometres east to the Heads of Sydney Harbour.

Cockatoo Island was used as a (~ natural ...) prison in the days of the first British invasion. It's only some 400 metres off the modern suburbs Balmain or Birchgrove ... but very few few of the Pommies of that day and invasion could swim - so it was an effective prison in its day - before construction of more regular ( and larger ) prisons and gaols.

All this works pretty well as a rather muddled song ... bridging from the initial Convict era (~ 1788 to about early 1850s (first public admission of gold strikes) ... and the beginning of our Goldrush era.

I guess it does sound very much an A L Lloyd song - a (re)construction from oral sources ... possibly noted in his exercise book 'between the World Wars' ... and re-visited in England and in the era of the postwar British FolkSong revival - and the ambience of Cecil Sharp House!

Regard(les)s,

Bob