As means of transport, they were the equivalent of the tortoise and the hare. One was a streamlined world-beater, the other a comparative slowcoach whose design was described by the kindest as "something of an oddity". Needless to say, the plodder overtook the blue streak and helped transform travel for the average Briton.

How did it happen? There was only one Mallard but 155,350 ugly ducklings, which is how many viewed the Ford Popular. It's an almost forgotten quirk of history that craftsmen in Doncaster produced both icons. Some built the locomotive, which 70 years ago this month broke the speed record for a steam engine and within two decades, others down the road were instrumental in ending the railway's domination and hastening the arrival of Dr Beeching with his axe.

He savaged the rail network, in part as a consequence of what was advertised as the world's cheapest saloon car. The Popular may not have been pretty but it was aptly-named. It brought motoring to the masses for as little as £275, plus purchase tax of £115 14s 2d.

In its displays, Doncaster Museum doesn't pass comment on the town's role in the rivalry between road and rail, and it might have told a one-sided story had it not been for a civil engineer called John Jewison. Until his intervention, the museum's transport focus was on the vast Plant Works. There, over more than a century, 40,000 steam locos were built and repaired, most famously Flying Scotsman, and then Mallard, which, on a Sunday afternoon in July 1938, reached an unbeaten 126mph between Grantham and Peterborough.

Compared to the homage paid to trains, Jewison felt that Doncaster's contribution to car-making had been all but erased.

Despite being seriously ill, his response to this neglect was to scour the country for a pristine example of one of the 63,500 Ford 103E Populars assembled in the town between 1955-59.

One was found in Uxbridge, Middlesex, and it's thanks to him that the basic family runabout, in Richmond Blue, its tax disc now five years out of date, returned home to become an exhibit.

He died two weeks later and his widow, Christine, presented it to the museum. Like Mallard and Flying Scotsman, now 85, its Popular has also reached a significant milestone – this year is the car's 50th birthday.

Mrs Jewison revealed that it was she who actually bought it for the town, paying the owner £2,200 despite being no admirer of the model. "John and I were Austin A35 fans," she said, "and to us, the Popular was rather crude. It was known as the sit-up-and-beg Ford."

Even enthusiasts acknowledge its shortcomings. A website devoted to it describes no-frills motoring, only three forward gears, 0-50 in 24 seconds, dated styling, a side-valve engine more in keeping with the 1930s, and the "poverty" of its finish: a single vacuum-powered windscreen wiper, no heater, vinyl trim, and hardly any chrome.

Still, despite a top speed of only half that of Mallard's, it liberated Everyman here and abroad. The president of the Traditional Car Club of Doncaster was determined the town should not forget.

"The car industry here came and went in a relatively short time and John was concerned there was nothing visible to record the fact. Doncaster wasn't just a railway town, and he thought it was wrong that significant other history was being ignored" said 70-year-old Mrs Jewison, who admits to enjoying a brisk spin in her Rover P6 3.5-litre V8.

"When he embarked on his search for a suitable Pop, he regarded it as a kind of homecoming for the car. His hope was that it would occasionally be driven around the town as a reminder of what Doncaster did for motoring. I think he'd be rather disappointed that it never leaves the museum, but at least, thanks to him, it has official recognition."

His concern about the burying of the past was justified. In the local history section of the public library, a single green file is almost all there is marking Donny as a motor town. One account among the contents suggests it happened by accident, courtesy of Hitler.

A huge engineering press, built in Scotland for a customer in France, was en-route there by rail when war broke out. To prevent it falling into German hands, the press was shunted into a siding in Doncaster. Later, it became part of the war effort and was housed in former railway wagon works in Carr Hill where a company called Briggs Motor Bodies, which had relocated from bomb-damaged Essex, used it to produce parts for aircraft.

After the war, Briggs stayed on to resume its previous job. They produced bodies for several vehicle manufacturers, including Jowett of Bradford. In 1953, their biggest customer, Ford, took over Briggs and within two years production of the Popular switched completely to Doncaster.

It involved the most ambitious expansion programme of its kind in the country, and cost £6m. The factory by then had a workforce of 1,300, for whom a perk was the chance to buy one of the cars at a reduced price. Such was the public demand, fuelled by advertising campaigns and sales drives like National Popular Week, that employees had to wait up to a year for one of the 80 models they were producing each day.

The Suez crisis of 1956 and the petrol rationing it led to, was a brief setback. It wasn't long before the Popular was back in full production and the factory was also turning out Escorts, Squires and Thames vans.

By August 1959, a vehicle was coming off the assembly line every three-and-a-half minutes and Doncaster was the first plant in Europe to mass-produce cars from start to finish.

Long gone was Henry Ford's edict that a customer could have a car in any colour as long as it was black. By then, the Popular was available in a range of shades, including Lichfield Green, Bristol Fawn, Winchester Blue and Newark Grey, as well as black. Extras were available too. A second wiper cost the equivalent of £2.47, a radio kit was nearly £20, and ashtrays were 38p

In the end, design innovations put paid to the Popular – the last one rolled off the line on August 14, 1959 – and national politics undermined Doncaster as a car-making centre. A report among the library's records claims that Ford was considering expanding in the town, but there were government incentives to go to Merseyside and a plant was built at Halewood. For a time production continued in Doncaster and a design office was retained. But by 1971 all trace of the Ford presence had gone, and the last site it occupied is now a Tesco.

A few sheets of paper in a folder in the library seems a scant archive for an enterprise which in all produced 100,030 vehicles and helped to revolutionise life in Britain.

Through one man's determination, Doncaster's contribution is marked in at least one tangible way. For John Jewison it was, says his widow, a passion with a personal twist.

The Popular they donated to the town has the registration number YBJ 885. "He used to tell me the letters stood for 'Your Beloved John'."

Doncaster Museum and Art Gallery, Chequer Road. Open Monday-Saturday 10-5 Sunday 2-5 Admission free.