"Prog" for food occurs in "Orderly Day, or The orderly's song" on which we have a thread still ongoing ~~last entry only about a fortnight ago ~~

"For spotted dog's magnificent prog
And so is Irish Stew..."

This appears to have originated at Catterick Camp, Yorkshire during WW1, and to be sung in schools in England & Scotland, also according to one post in NZ, having been included in a school songbook by Walford Davies, sometime Master Of The King's Musick.

No Australian connection mentioned; so perhaps 'prog' not an exclusively Australian usage at that?

~M~