I remember Alistair having a go at explaining the words "ill-throckit/ill-throcked dog" to a Sydney audience as being one of those nasty little dogs full of false bravado, but ultimately powerless. It's definitely not an Australian expression, but there are plenty of those little yappy dogs. There is a definition of "throck" as "confused crowd or throng" too as well as one relating to oxen.

In my recall of him singing the song live, I would have transcribed the last half of the final verse as:

In childhood dreams I've scaled the wall
Well schemed by empires tae haud us back
And my hair thin falls watchin' callants braw
Envoy a Union Jack