Will supersonic air travel's return be another white elephant?

In December 1967, on an airfield in Toulouse, France, a hangar door swung ceremoniously upward to reveal a wonder of the age: the prototype of Concorde.

An Anglo-French creation, this gorgeous, delta-winged, dart of an aircraft was capable of flying at twice the speed of sound. Its revolutionary aluminium alloy skin could expand by a third of a metre to cope with the frictional heating at such speeds. It was a true marvel of jet power, metallurgy and aerodynamics.

But despite its technical prowess, Concorde, with just 128 passenger seats, was a financial white elephant.…