Watch Stuart Leithes' story on the space age train which was ahead of its time
It was hoped it would be the train of the future.
Forged in the white heat of Harold Wilson's technological revolution a group of engineers believed that a train riding on a cushion of air would be the future of public transport.
Tracked Hovercraft Limited was set up in 1967 to use Government funding to develop the system.
And a test track was built at Earith near Ely - running alongside the man-made Old Bedford River.
50 years on all that's left of the track are a series of isoltated concrete supports - only visible from a footpath.
The reason for the failure - the fenland on which they tried to build the test track.
Research Test Vehicle 31 hovered on air produced by fans and was propelled by a Linear Induction Motor developed by Professor Eric Laithwaite which used magnetic fields to create motion.
You can see more on that in the video below.
Potential routes were drafted - including one to the proposed Thames Estuary Airport that was never built. By 1973 around £5m had been spenton the hovertrain project - and the Government decided to pull the plugand gave its backing to the Advanced Passenger Train instead.
RTV 31 was kept at Cranfield University in Bedfordshire for 20 years.And in 1996 it was saved from being scrapped by the Railworld centre at Peterborough.
Railworld and Cambridge University's archaeology departmentrecently produced this video about the hovertrain project.
Trains that use magnetic levitation, or 'mag-lev' systemswere later developed and still run in Japan, China and South Korea.
It's not the first time the region was involved in pioneering travel schemes.Also in the 1960s a scale model of the supersonic jet Concorde was flown over Bedfordshire in preparation for its launch.
It will be the task of historians and enthusiasts to argue over whether the end of the RTV 31 project was a missed opportunity.