Two feet, four, six . . . 7ft off the ground. After repeated nervous, muddy attempts, Bud Ekins, a motorcycle stunt rider, coaxed the old Triumph into the air, flew over the strands of fake barbed wire and into the history books. The sequence helped make The Great Escape a cinema classic and turn Steve McQueen into an international star. It also made Ekins, who doubled as McQueen, a legend among fellow riders.

In stunt-riding circles, the jump is still regarded as one of the most technically skilled — and controversial — performed for the big screen. Controversial because Ekins later claimed it was done on a standard, factory-built Triumph. Some film historians say such a jump could not have been accomplished except by special effects or on a highly modified machine. Forty-six years after The Great Escape was made, The Sunday Times has solved the mystery by reconstructing the jump.

In the film, Virgil Hilts, the Cooler King, played by McQueen, is fleeing from the Germans and trying to escape to Switzerland. He seizes a military motorbike and a high-speed chase ensues through the rolling fields near the Swiss border. Though McQueen did much of his own stunt riding, the jump was deemed too risky by the film studio’s insurers and McQueen nominated Ekins, a friend who ran a motorcycle repair shop in California, to do it. The scene required propelling the heavy bike high enough to get it over the first of two fences that film crews had built to resemble the border.

For its day, it was a daring feat, no less so for the fact that the barbed wire was actually little strips of rubber tied around normal wire, made by the cast and crew in their free time. Even that concession to safety was not out of concern for Ekins, but because the script required McQueen to become entangled in the wire before surrendering.

After the film was released, Ekins kept quiet about the jump. His silence helped perpetuate the widely held belief at the time that it was McQueen who had cleared the fence and not a stunt double, though McQueen never made this claim. Before his death in 2007, Ekins recounted the experience in a rare interview. “When I was in the air it was dead silent,” he said. “\ was hard. It just went bang, then it bounced. I made it on the first pass. I filmed it. That was that.”

Ekins later admitted numerous practice attempts had failed. “The effects man put a piece of string across at all these different heights,” he recalled. “The first time, I’d take a run at it and jump maybe 2ft off the ground. Then we would take a shovel and dig this natural ramp, changing the angles on it.”

The first stage in our reconstruction was to find a bike that matched the original Triumph Tiger used in the film. The modern Tiger is nothing like its ancestor so we settled on a bike called the Métisse Steve McQueen Desert Racer, a replica of a bike built by McQueen and Ekins in the 1960s. Our replica was built by Gerry Lisi, a British enthusiast, using genuine Triumph parts and home-machined components. Though not identical to the Tiger used in the film, the Desert Racer is comparable in size (albeit somewhat lighter at 297lb versus 365lb) and performance (it uses the same 650cc Triumph engine, giving a top speed of about 90mph). Triumph motorbikes were considered world beaters in their day; in 1965 five of the top 20 finishers of the Daytona 200 were on Triumphs.

But good though it was, by today’s standards the 1960s Triumph was a clunky old machine and quite unsuitable for jumping — all the more reason to marvel at Ekins’s achievement, if it was genuine. We were about to find out.

Next we brought in Steve Colley, three times British trials bike champion and one of the best motorcycle jumpers in the business. Reaching a height of 7ft would normally be a breeze for Colley on a specially built stunt bike. But they typically weigh only 150lb — half that of the Desert Racer — with double the power-to-weight ratio.

Colley was sceptical about whether he could do it (“Ekins and those guys were used to riding heavy motorcycles and making them do incredible things. No one would dare today. It’s a lost art.” Pause. “But I’ll give it a go.”)

As a substitute for Bavaria, the location used for The Great Escape, we chose Carswell golf and country club near Wantage, Oxfordshire, where the rolling fairways matched the landscape of that region. A line of fencing was built with logs to represent the Swiss border.

With everything in place, Colley made his first run. Like Ekins, he could initially manage no more than a couple of feet off the ground. “I’m tugging on these handlebars for all I’m worth and all I’m getting is bunny hops,” he said.