Range aside, wasn't the problem with London-Sydney that most of the route is over land, and can't be supersonic for noise reasons? At least, IIRC, that's what k

Range aside, wasn't the problem with London-Sydney that most of the route is over land, and can't be supersonic for noise reasons? At least, IIRC, that's what killed the Concorde in the potentially very lucrative US east-west coast market.