Originally Posted by Raffles
It would cost you 200,000 BA Miles for the same ticket (albeit with a better seat) - a truly pathetic 0.66p per mile of value.
Indeed. Since the OP now mentions he's looking for 2 seats though, if he could get (has?) the AmEx card and voucher (to the OP - see the ULTIMATE guide if you don't know what I'm babbling on about!) and if (the BIG if!) he could get the 2 J seats LON-SYD-LON for the price of 1, it becomes better value.
Not sure I'd MFU to Oz - I'd look to GUF though, perhaps.