Some time in the middle of the next decade a revolutionary new engine will propel a reusable space plane called Skylon towards the heavens, hopefully changing the way we escape our atmosphere for ever.

The Synergetic Air-Breathing Rocket Engine (Sabre) isn't a product of Nasa or a super-wealthy space entrepreneur. It's the brainchild of a quiet, British engineer called Alan Bond. And, from its base in a science park near Oxford, his company Reaction Engines is getting closer to perfecting its design. Bond has spent his working life trying to solve a problem that most people haven't even considered; space crafts powered by traditional rockets are far too expensive and unreliable, and will never provide humankind with the tools to explore our solar system and beyond.

"On the face of it space rockets are an extremely good and established way of getting craft into space," he says, "but they are incredibly expensive, so much so that a typical commercial launch will cost somewhere in the region of £100m, which is equivalent of buying a Boeing 747 before using it just once and sending it to the crusher."

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There is strict security at the site with a sign warning of an "elevated" threat, though this is more to do with an Atomic Energy Research Establishment site next door. Bond is furtive crossing the car park to the test site though, admitting that there is an undisclosed UK military interest in Sabre. He won't go into details, pointing out that of far greater concern is corporate espionage against the £360m project; the idea behind Sabre is truly revolutionary.

The Sabre design is so effective because it operates as a traditional jet engine at take-off and during the ascent, before "transforming" into a powerful hydrogen-burning rocket engine to send the Skylon at Mach 25 beyond Earth's atmosphere. This allows the Skylon to operate like a plane and re-enter the atmosphere, before landing on a normal runway.

It sounds "simple enough" admits Bond, but to get it right the firm has had to develop a whole host of technologies, including a heat exchanger and pre-cooler to cope with the drop in temperature from 1,000C to -140C in a fraction of a second, as high-speed air hits the engine.

This hot air can't be allowed to frost, which would doom the craft to oblivion. Exactly how this is prevented is a closely guarded secret, but Bond says that the firm "is set to announce up to a dozen patents soon". Space industry insiders will be watching closely.

The Skylon craft itself will be equally revolutionary; using ultra-lightweight material it will essentially be one huge hydrogen tank, making it light enough for easy re-entry. The result will be a craft that costs £500m to buy and just £3m to launch per mission that will be "operated by a [ground] crew of just 50 and be able to manage a return trip with payload in just two days before people are able to go again."

Bond admits the challenge is vast, though he was clearly happy that his project has just been boosted by a positive feasibility study from the European Space Agency and a consortium of big aerospace players.

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To get to this stage he has "hung around" for three decades, battling various politicians, overcoming failed projects, dodging the constraints of the Official Secrets Act and scrambling around for funding.

This battle goes all the way back to a project he was working on as a consultant for British Aerospace in the 1980s which was killed off by government budget cuts. "My dream was always about finding a way of getting into space far more cheaply and easily, but I had no fixed opinion about who would foot the bill for it," he said. "But after the project failed, I was advised by a very wealthy businessman to get into the business of selling space planes directly."

Now Reaction Engines gets most of its funding from "high-net worth individuals", and it is the Government who is the minor player, investing just £60m in the plan, though Bond admits he has a soft spot for the "visionary" David Willetts, the Minister for Science who has backed the project.

Space travel is currently dominated by Richard Branson's Virgin Galactic and Elon Musk's SpaceX, challenging a market traditionally run by governments and major aerospace players. The reason for this, Bond says, is a realisation that space travel can be done cheaper. Bond admires Elon Musk but doesn't "believe his costings" or see his SpaceX craft as a genuine rival. He's more dismissive of Richard Branson, whom he calls "that man" who messes around with taking people "up and down", rather than genuinely launching them into orbit.

Bond is quick to wander off into space dreams – he's certain we'll be living on other planets within three generations – but he's convinced there is a demand for space flight and a business case that will see the sale of up to 90 of the £500m Skylon aircraft. "One of the things we noticed back in 2010 was that the space industry didn't go into recession," he said. "Rather it saw double digit growth at times. And clearly what's holding it back is an inadequate transport system."

With a payload of 15 tons and an ability to service "space nodes" (fuel stations) he hopes Skylon will fill that gap. "We need to open space travel up to everyone if we are ever to get off this grim rock," he says.

That's an incredibly bold ambition, especially for the inventor of a craft that hasn't flown yet. But somehow you get the feeling that this 70-year-old space pioneer is in it for the long haul, and what to many sounds like a flight of fancy, to him is just another practical problem to be overcome.