This remarkable achievement, however, almost never got off the ground. Its origins stretch back to 1956 when Sir Morien Morgan of the Royal Aircraft Establishment started work on “supersonic transports” with a view to taking on America in aerospace innovation. At the same time, France was working on a similar project, but both countries’ efforts came under threat as objections were raised about costs and noise pollution. To salvage their schemes, the two nations signed a treaty: the British Aircraft Corporation and France’s Aérospatiale would work together to make supersonic dreams a reality… More here.
The world really did get bigger when Concorde stopped flying.