The futuristic Railplane that never got on track

The elegant, streamlined cigar shaped carriage was the height of luxury, with stained glass, carpets, armchairs and individual table lamps. Sliding doors - the height of opulence - allowed people on and off the trains at elevated stations.

The Railplane was suspended from a rail and powered by electric propellers on both ends. Beneath the train, suspended 16 feet above the ground, were wheels which rested on another rail and helped stabilise the carriage.

A braking system on the top rail would hold the train still at stations, and the propellers could also be reversed.

One of Bennie's invited guests on the test run noted that "the Railplane operated with perfect smoothness and passengers only knew the car was moving by gazing out of the window at the passing landscape.

"There was no bumping over rails, smoke or whistle shrieking. A ride in the coach is sheer delight."

Bennie, the son of a hydraulic engineer, was aiming high. He claimed the Railplane would reach speeds of 120 mph and could take passengers from Glasgow to Edinburgh in 20 minutes. There was even talk of a London to Glasgow journey in three and a half hours.

But the Railplane was destined to go no further than its test track, over disused LNER sidings at the Burnbrae Dye Works. Bennie, 39 at the time of the launch, went bankrupt and died 24 years later virtually unknown.

"It never really left him," said John Messner, curator of transport and technology at Riverside Museum in Glasgow.

"He thought it could be the future for passengers and for freight."

Bennie came up with the idea in 1921 and gained a patent for the design in 1923. Lacking formal engineering qualifications, he employed a consultant engineer, Hugh Fraser, to undertake the technical design.

"By the 1920s the railways were straining at the seams," Mr Messner said. "There was competition between freight transport and passenger transport. His concept was to separate the two without the requirement for a new railway network."

The passenger Railplane would travel above the freight.

"It was a striking futuristic vehicle," he added. "This was the only prototype of its kind. He took inspiration from a well publicised monorail in Germany where carriages ran beneath the rail track."

Bennie, who invested £150,000 of his own money - £9.8m today - was certain of its success. He said it was 'as great a step in the evolution of rail transport as the motor car was to the stagecoach in road transport.'

"I'm sure he was convinced [on the launch day] that that would be that," Mr Messner said.

But he was never able to secure the financial backing to get the Railplane on track.

"For a start, this was 1930 - the start of the depression," Mr Messner said. "Investment in new, untried systems was scarce. Technology was still progressing and it's unclear if the 20 minute journey from Glasgow to Edinburgh would be feasible. From a 400 foot test track it's hard to predict."

There was also the issue that the track did not have to encounter railway bridges or tunnels, unlike existing rail lines.

"You have to come up with a solution to get past them - a problem we still face today," Mr Messner added. "He had not addressed that."

Diesel and electric trains were developing 'quite fast' services at the time too. "It could have just been the wrong place, wrong time," Mr Messner said.

"Events in the 1930s might just have overtaken them."

It was unclear if the lack of investment was the reason for the project's failure, or if the innovative techniques were a step too far, and scared potential clients (the transport authorities) away. In either case, the result was the same and Bennie was eventually declared bankrupt in 1937.

The track was demolished in 1941 for the wartime scrap metal campaign and the Railplane, which lay rusting in a field at Milngavie, was sold for scrap in 1956.