Just a warning - check www.ozbargain.com.au or other bargain sites for feedback and updates.

As happens on slickdeals, the promo 20% off will likely be exhausted as soon as it's given a bit of airtime on the Australian bargain sites.

I'll move this across to Budget Travel now, but it's still worth a look for this 2010 QF LHR-SYD routing, provided you're aware that this promo might be gone now or some time into your booking.

Here's a Flight Centre 20% off Paypal promo - AU domestic, up to a $200 cashback:
http://www.ozbargain.com.au/node/18399