Finnair is not an obvious choice for Australia but they offer a quality service and, at the right price, or if everyone else was full, could be an interesting choice. You fly from Heathrow or Manchester to Helsinki (which prides itself on the ease of its connections) and from there to Hong Kong where you connect with Qantas to Australia. At the more extreme end of options, the Russian airline, S7 (a member of OneWorld), desreves a mention. It offers fares to Sydney via Moscow. You fly from London to Moscow with BA and then with their partner Etihad to Abu Dhabi and on to Sydney. The only involvement of S7 is selling the ticket. If you were able to get stops at both cities (and get the visa for Moscow), it could make an interesting trip.