Since the inauguration of the first commercial regular long-distance air services in the 1950s, the relative distance between London and Sydney (commonly labeled as the “kangaroo route”) has been substantially reduced. When the route was serviced by propeller planes (Super Constellation), the segment took two and a half days and 7 stops to be serviced (with an overnight stay in Cairo and Singapore). The introduction of the 747 in the 1970s reduced this route to 26 hours and two stops. A more fuel-efficient and longer-range 747-400 improved the route by 3 hours because only one stop was required.
In 2006, for the first time, a direct flight became a possibility with a new generation of long-range aircrafts such as the 777-200LR. However, this route is at the extreme limit of serviceability as dominant winds would only make an east-west non-stop full load leg possible. Thus a “direct” flight between London and Sydney still involves a technical refueling stop in Dubai (Emirates) or Singapore (Qantas). With the introduction of the Dreamliner (B787-9) in 2014, a full direct flight became possible with no technical stop, taking just over 19 hours. Considering technical limitations linked with the ratio speed/fuel consumption, it is unlikely that the travel time between London and Sydney will become lower than 19.5 hours of a direct flight.