London - It is a journey that takes more than 20 hours by conventional passenger plane - enough time for several meal breaks and a string of movies.
But soon British holidaymakers will be able to touch down in Sydney having barely digested their lunch.
Flights from the UK to Australia could be reduced to about four hours thanks to new engines developed in Britain, experts say.
Rocket engines capable of propelling an aircraft to Mach 5.5 – five times the speed of sound – are being developed for use on commercial airliners by Oxfordshire-based firm Reaction.
Dr Graham Turnock, of the UK Space Agency, told the Space Conference in Newport: "This is not sci-fi. This is not a pipe dream. This is literally in the works. It has the potential to turn air travel on its head. Certainly the way you conceive air travel will completely change in ten years’ time."