Louis Brennan and his assistants pose with a model of his invention; the Brennan Monorail. (Photo by Hulton Archive/Getty Images). May 1907

The Brennan Monorail at White City, London. Willows' airship is visible in the background. (Photo by Hulton Archive/Getty Images). April 1910

The mono rail service at the Wembley Empire Exhibition, London. (Photo by Topical Press Agency/Getty Images). Circa 1924

Passengers seated in a surrey cart looking at a new monorail service in Houston, Texas. (Photo by Evans/Three Lions/Getty Images). Circa 1950

A monorail train on a test run at Fuhlingen, Cologne. (Photo by Horace Abrahams/Getty Images). 1952

A hanging monorail train moves along the seven mile Wuppertal Monorail System in Germany, just above the traffic. (Photo by Orlando /Three Lions/Getty Images). Circa 1956

Portrait of the MP and Chairman of the company formed to build the first mono-rail between London and London Airport, Sir Alfred Blossom, at his Westminster office. (Photo by Fox Photos/Getty Images). 22nd January 1958

Monorail rides at Disneyland, California. (Photo by Keystone Features/Getty Images). December 1960

A “Monorail Locomotive and Man Riding Carriage” devised by Qualter Hall & Co of Yorkshire for use in collieries. It is hoped that it will enable men, supplies and coal to be taken to and from the coal face more quickly. (Photo by Fox Photos/Getty Images). 1965

A monorail train at Butlin's holiday camp at Minehead, Somerset, circa 1967. (Photo by Evening Standard/Hulton Archive/Getty Images)

The French rocket-boosted hover train unit, known as the “aerotrain monorail”, which set a new world speed record in 1967. (Photo by Express Newspapers/Getty Images)

A trial monorail train. (Photo by Leonard Burt/Central Press/Getty Images). 22nd December 1971

Space Mountain at Disney World in Florida. (Photo by Central Press/Getty Images). 26th February 1979