If you want the 747 and a cheap fare why not look at Malaysia Airlines. They have some special fares out at the moment from LHR to AUS. You would fly 744 LHR – KUL and either 744 or 772 KUL – MEL depending on the day and time of travel. Alternatively if you prefer BA, most fares allow you to route via Sydney at no extra cost and so you can take the BA 744 LHR-SIN-SYD or LHR-BKK-SYD and then catch and QF internal flight down to MEL (included in the fare). Another option would be to take BA LON – SIN and then QF SIN – MEL. That way you are travelling two thirds of the way with BA. BA/QF have close ties and so the fares offered allow travel on either carrier. One tip! Look at the Qantas fares. They’re sometimes cheaper and you can use BA services!