Hello bestseller and Mod Gadge,

This is such an interesting question because it has never been resolved.
I think Gadge can given cogent arguments for a later start date for the Code.

In retrospect, the evidence is there for this, as Gadge points out.
Victa Cuttings from the 1960s should have some reference to it to
indicate its existence at that time. No brochure mentions it either!
I do not know of a 1960s Victa with a Code on it (a feature of the
Code itself was its placement on the mower).

I do not own a 1970s range brochure, but the 1971 Range (1970-71) certainly
suggests the Code was quite recent:-
https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=61949#Post61952

The Powerhouse Museum record is a great find.
One of these (in poor condition) is offered on Fleabay for a silly amount:- HERE.

Good ol' peg board.
----------------------------
Jack