I note that on qantas.co.uk, one can book both "business saver" and "first saver" fares from LHR - SYD, which I can't find on the .com.au site.
£1400 saving on full-fare J, and £2300 in F.
What the... ?!
Only catch is total inflexibility, and minimum stay of "no sooner than the first Sunday after departure".
Still count as J and F for points/SC earn.
No such luck on the trans-Pacific routes, surprise, surprise!