You can imagine the time I had living in Earls Court in the Seventies, when it was still full of Aussies and called Kangaroo Valley....... 
I used to make sausages on an organic farm a few years ago. The 'rusk' is a LOT cheaper than Golden Crumb from the tackle shop
The reason it's still so popular with most sausage makers is they sell their bangers by weight...and they soak the rusk in water overnight.....
We didn't.....and by God they were filling. We also did gluten free but they weren't as nice...you do need some rusk in there.